2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 806
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.
Action Taken When the DTCs Sets
* The module suspends all message transmission.
* The MIL and battery indicators will illuminate, along with several DIC messages.
* The vehicle may continue to run for several minutes, then will stall and not start.
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.
Reference Information
Schematic Reference
* Data Communication Schematics (See: Powertrain Management/Computers and Control Systems/Information Bus/Diagrams/Electrical
Diagrams)
* Control Module References (See: Testing and Inspection/Programming and Relearning)
Connector End View Reference
Component Connector End Views (See: Diagrams/Connector Views)
Description and Operation
Data Link Communications Description and Operation (See: Powertrain Management/Computers and Control Systems/Information
Bus/Description and Operation)
Electrical Information Reference
* Circuit Testing (See: Testing and Inspection/Component Tests and General Diagnostics/General Electrical Diagnostic Procedures/Circuit
