For 1990-2009 cars only
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 33: ECU Hardware Performance Special Memory FailureDTC C056D 34: ECU Hardware Performance RAM Failure
DTC C056D 35: ECU Hardware Performance ROM Failure
DTC C056D 36: ECU Hardware Performance EEPROM Failure
DTC C056D 39: ECU Hardware Performance Internal Electronic Failure
DTC C056E 41: ECU Software Performance Operational Software/Calibration Set Not Programmed
Circuit/System Description
This diagnostic applies to internal microprocessor integrity conditions within the trailer brake control module (TBCM). This diagnostic also addresses if the TBCM is not programmed.
Conditions for Running the DTC
C056D 33, C056D 34, C056D 35, C056D 36 or C056D 39
| • | Ignition ON. |
| • | Runs once an ignition cycle. |
C056E 41
| • | Ignition ON, engine OFF. |
| • | Runs continuously. |
Conditions for Setting the DTC
C056D 33, C056D 34, C056D 35, C056D 36 or C056D 39
The TBCM detected a failure in its microprocessor.
C056E 41
The TBCM is not programmed.
Action Taken When the DTC Sets
| • | The trailer brake control will be disabled at the end of the current brake apply for the remainder of the ignition cycle. |
| • | The driver information center (DIC) will display Service Trailer Brake System. |
Conditions for Clearing the DTC
| • | The condition for the DTC is no longer present. |
| • | The TBCM clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles. |
Reference Information
Schematic Reference
Trailer Brake Control Schematics
Connector End View Reference
Description and Operation
Trailer Brake Controls Description and Operation
Electrical Information Reference
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Verify that DTC C056E is not set.
- Verify that DTC C056D is not set.
| ⇒ | If the DTC is set, program the TBCM. |
| ⇒ | If the DTC is set, replace the TBCM. |
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for TBCM replacement, setup, and programming
