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.