2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 850

2010 Cadillac Truck Escalade EXT AWD V8-6.2L Page 850

4. Verify the scan tool BMC Primary Piston Position Sensor A parameter is less than 1 V.

瀚慖f greater than the specified range, test the signal circuit terminal 3 for a short to voltage. If the circuit tests normal, replace the EBCM.

5. Install a 3A fused jumper wire between the signal circuit terminal 3 and the 5 V reference circuit terminal 2. Verify the scan tool BMC

Primary Piston Position Sensor A parameter is greater than 4.5 V.

瀚慖f less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace

the EBCM.

6. Verify the scan tool BMC Primary Piston Position Sensor B parameter is less than 1 V.

瀚慖f greater than the specified range, test the signal circuit terminal 1 for a short to voltage. If the circuit tests normal, replace the EBCM.

7. Install a 3A fused jumper wire between the signal circuit terminal 1 and the 5 V reference circuit terminal 2. Verify the scan tool BMC

Primary Piston Position Sensor B parameter is greater than 4.5 V.

瀚慖f less than the specified range, test the signal circuit for a short to ground or an open/high resistance. If the circuit tests normal, replace

the EBCM.

8. If all circuits test normal, replace the brake master cylinder piston position sensor. If DTC resets, replace the EBCM.

Repair Instructions

Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the diagnostic procedure.

* Brake Master Cylinder Primary Piston Position Sensor Replacement (See: Brakes and Traction Control/Antilock Brakes / Traction Control

Systems/Braking Sensor/Switch/Service and Repair)

* Control Module References (See: Testing and Inspection/Programming and Relearning) for EBCM replacement, setup, and programming

C126C

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.