Antilock Brake System

DTC C056D

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview)provides an overview of each diagnostic category.



DTC Descriptor
DTC C056D 34
- ECU Hardware Performance RAM Failure

DTC C056D 35
- ECU Hardware Performance ROM Failure




Circuit/System Description

This diagnostic applies to internal microprocessor integrity conditions within the Electronic Brake Control Module (EBCM). This diagnostic also addresses if the EBCM is not programmed.


Conditions for Running the DTC

* Ignition is ON and DTC C056D runs once an ignition cycle.
* The EBCM detected a failure in its microprocessor.



Conditions for Setting the DTC

The EBCM detected a failure in its microprocessor. The EBCM is not programmed.


Action Taken When the DTC Sets

* The EBCM will be disabled at the end of the current brake apply for the remainder of the ignition cycle.
* The Service Brake System will be displayed on the Driver Information Center (DIC).



Conditions for Clearing the MIL/DTC

* When the condition for the DTC is no longer present.
* The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.



Reference Information
Schematic Reference

Antilock Brake System Schematics (Except JL7) (Antilock Brake System Schematics (Except RPO JL7))Antilock Brake System Schematics (JL7) (Antilock Brake System Schematics (With RPO JL7))
Connector End View Reference

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)for scan tool information


Circuit/System Verification

Ignition ON, observe the DTC information with a scan tool. DTC C056D should not set.

If DTC C056D 35 failed this ignition, replace the EBCM.
If DTC C056D 34 failed this ignition, program the EBCM.



Circuit/System Testing

C056D 34

Program the EBCM. If DTC C056D 34 sets after programming, perform the following steps:

* If DTC C056D 35 is set, turn off the ignition, wait 30 seconds, turn ignition on, if DTC C056D 35 failed this ignition cycle, replace the EBCM.
* If DTC C056D 34 is set, turn off the ignition, wait 30 seconds, turn ignition on, if DTC C056D 34 failed this ignition cycle, program the EBCM.

• If DTC C056D 34 sets after programming, replace the EBCM.




Repair Instructions

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


Control Module References (Programming and Relearning)for EBCM replacement, setup, and programming