GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2008 🢒 STS 🢒 Driver Information and Entertainment 🢒 Cellular, Entertainment, and Navigation 🢒 DTC C056D

Diagnostic Instructions
    • Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
    • Review Strategy Based Diagnosis for an overview of the diagnostic approach.
    •  Diagnostic Procedure Instructions 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

Connector End View Reference

Component Connector End Views

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References 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 after completing the diagnostic procedure.

Control Module References for EBCM replacement, setup, and programming