2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2831
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0438
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
Showing posts with label * Ignition ON.. Show all posts
Showing posts with label * Ignition ON.. Show all posts
Tuesday, December 15, 2020
Monday, December 14, 2020
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2823
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2823
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0422
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0422
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2815
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2815
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0415
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0415
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2807
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2807
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0401
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0401
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
Sunday, December 13, 2020
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2799
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2799
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0256
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0256
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2791
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2791
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0249
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0249
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2783
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2783
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0232
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0232
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
Saturday, December 12, 2020
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2766
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2766
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0208
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0208
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2758
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2758
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0198
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0198
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
Friday, December 11, 2020
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2749
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2749
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U186A
DTC U186A
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC U186A
- Lost Communication With Transfer Case Control Module
Circuit/System Description
Modules connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and
commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the
serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an
availability indication of the transmitter module. Each message contains the identification number of the transmitter module.
Conditions for Running the DTCs
* The system voltage is between 9-16 volts.
* The vehicle power mode master indicates that the need for serial data communications.
Conditions for Setting the DTC
A supervised periodic message that includes the transmitter module availability has not been received.
Action Taken When the DTCs Sets
The modules is never signaled, therefore the specific subsystems will not function.
Conditions for Clearing the DTC
* A current DTC clears when the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U186A
DTC U186A
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
DTC U186A
- Lost Communication With Transfer Case Control Module
Circuit/System Description
Modules connected to the serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and
commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the
serial data circuits, for each virtual network. The messages are supervised and also, some periodic messages are used by the receiver module as an
availability indication of the transmitter module. Each message contains the identification number of the transmitter module.
Conditions for Running the DTCs
* The system voltage is between 9-16 volts.
* The vehicle power mode master indicates that the need for serial data communications.
Conditions for Setting the DTC
A supervised periodic message that includes the transmitter module availability has not been received.
Action Taken When the DTCs Sets
The modules is never signaled, therefore the specific subsystems will not function.
Conditions for Clearing the DTC
* A current DTC clears when the malfunction is no longer present.
* A history DTC clears when the module ignition cycle counter reaches the reset threshold, without a repeat of the malfunction.
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2737
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2737
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
C126C, C126D, C12E3, or U180F
DTC C126C, C126D, C12E3, or U180F
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC C126C
- Control Module Communication Bus B Off
DTC C126D
- Control Module Communication Bus B Off
DTC C12E3
- Control Module Communication Bus B Off
DTC U180F
- Control Module Communication Bus B Off
Circuit/System Description
The PTLAN serial data circuits are serial data buses used to communicate information between the control modules. The PTLAN serial data
circuits also connect directly to the data link connector (DLC) for programming purposes. If this serial data system is inoperative the modules will
still communicate with the scan tool due to other serial data systems but not with each other. Communication with the scan tool for the modules on
the PTLAN bus is through the serial data gateway module (SDGM) on the HSGMLAN serial data system.
Conditions for Running the DTCs
* Supply voltage to the modules are in the normal operating range.
* The ignition switch in any position other than START.
Conditions for Setting the DTC
The module setting the DTC has attempted to establish communications on the PTLAN serial data circuits more than 3 times.
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
C126C, C126D, C12E3, or U180F
DTC C126C, C126D, C12E3, or U180F
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptors
DTC C126C
- Control Module Communication Bus B Off
DTC C126D
- Control Module Communication Bus B Off
DTC C12E3
- Control Module Communication Bus B Off
DTC U180F
- Control Module Communication Bus B Off
Circuit/System Description
The PTLAN serial data circuits are serial data buses used to communicate information between the control modules. The PTLAN serial data
circuits also connect directly to the data link connector (DLC) for programming purposes. If this serial data system is inoperative the modules will
still communicate with the scan tool due to other serial data systems but not with each other. Communication with the scan tool for the modules on
the PTLAN bus is through the serial data gateway module (SDGM) on the HSGMLAN serial data system.
Conditions for Running the DTCs
* Supply voltage to the modules are in the normal operating range.
* The ignition switch in any position other than START.
Conditions for Setting the DTC
The module setting the DTC has attempted to establish communications on the PTLAN serial data circuits more than 3 times.
Thursday, December 10, 2020
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2729
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2729
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0170
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0170
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2721
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2721
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0165
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0165
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2713
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2713
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0159
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0159
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
Wednesday, December 9, 2020
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2705
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2705
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0156
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0156
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2697
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2697
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0146
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0146
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2689
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2689
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0140
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0140
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
Tuesday, December 8, 2020
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2681
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2681
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0134
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0134
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2673
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2673
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0129
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0129
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2665
2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2665
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0123
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
6. If equipped, ignition ON, verify that a test lamp illuminates between the communication enable circuit terminal OR the accessory wakeup
circuit terminal and ground.
瀚慖f the test lamp does not illuminate, test the circuit for an open/high resistance. If the circuits test normal, replace the BCM.
7. Ignition OFF for 60 seconds, test for less than 5 ohm between the serial data circuit terminals and the appropriate DLC terminal listed below:
* Class 2 serial data circuit terminal 2
* Low speed GMLAN serial data terminal 1
* High speed GMLAN serial data terminal 6 or 14
瀚慖f greater than the specified range, test the serial data circuit for an open/high resistance between the non communicating control module
and a control module setting the DTC or a serial data splice pack.
8. If all circuits test normal, replace the control module that is not communicating.
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.
* GMLAN Wiring Repairs (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic
Procedures/Wiring Repairs/GMLAN Wiring Repairs)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for control module replacement, setup, and
programming
U0123
DTC U0100-U02FF (without HP2)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions) provides an overview of each diagnostic category.
DTC Descriptor
Refer to Control Module U Code List (See: Diagnostic Trouble Code Descriptions/Control Module U Code List).
Diagnostic Fault Information
Circuit/System Description
The serial data circuit is the means by which the control modules in the vehicle communicate with each other. Once the scan tool is connected to the
serial data circuit through the DLC, the scan tool can be used to monitor each control module for diagnostic purposes and to check for diagnostic
trouble codes (DTCs). When the ignition switch is in RUN, each control module communicating on the serial data circuit sends a state of health
(SOH) message to ensure that the control module is operating properly. When a control module stops communicating on the serial data circuit, for
example if the module loses power or ground, the SOH message it normally sends on the serial data circuit disappears. Other control modules on
the serial data circuit, which expect to receive that SOH message, detect its absence; those control modules in turn set a DTC associated with the
loss of SOH of the non-communicating control module. The DTC is unique to the control module which is not communicating and one or more
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