2010 Cadillac Truck Escalade/ESV RWD V8-6.2L Page 2212
DTC P0641 or P0651 (ECM)
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)provide an overview of each diagnostic category.
DTC Descriptors
DTC P0641
- 5 V Reference 1 Circuit
DTC P0651
- 5 V Reference 2 Circuit
Circuit/System Description
The engine control module (ECM) has 2 internal 5 V reference busses called 5 V reference 1 and 5 V reference 2. Each reference bus provides 5 V
reference circuits for more than one sensor. Therefore, a fault condition on one 5 V reference circuit will affect the other 5 V reference circuits
connected to that reference bus. The ECM monitors the voltage on the 5 V reference busses.
Conditions for Running the DTC
* The ignition is in Unlock, Accessory, Run, or Crank.
* The ignition voltage is more than 5.23 V.
* DTCs P0641 and P0651 run continuously when the above conditions are met.
Conditions for Setting the DTC
The ECM detects a voltage out of tolerance condition on the 5 V reference 1 or 2 bus for more than 0.5 s.
Action Taken When the DTC Sets
DTCs P0641 and P0651 are Type A DTCs.
Conditions for Clearing the MIL/DTC
DTCs P0641 and P0651 are Type A DTCs.
Diagnostic Aids
The 5 V reference 1 bus provides 5 V to the following sensors:
* B74 manifold absolute pressure (MAP) sensor
* B150 fuel tank pressure (FTP) sensor
* B107 accelerator pedal position (APP) sensor 2
* B1 air conditioning (A/C) refrigerant pressure sensor
* B37B engine oil pressure (EOP) sensor
* B23 camshaft position sensor
The 5 V reference 2 bus provides 5 V to the following sensors:
* B107 APP sensor 1
* Q38 throttle position sensor 1 and 2
* B26 crankshaft position sensor
It may be possible to locate the fault by disconnecting one component at a time from the 5 V reference circuit while viewing the 5 V Reference
Circuit parameter on the scan tool. The scan tool parameter would change fro Fault to OK when the source of the fault is disconnected.
If all 5 V reference components have been disconnected and a Fault is still indicated, the fault may exist in the wiring harness.
Reference Information
Schematic Reference
Engine Controls Schematics (See: Diagrams/Electrical Diagrams/Powertrain Management/System Diagram)
