Trailer Brake Controls

DTC C0561

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 C0561 F0
- System Disabled Information Stored Invalid Serial Data Received

DTC C0561 F1
- System Disabled Information Stored Invalid Serial Data Received




Circuit/System Description

Diagnostics are used to determine whether or not there is a fault with the brake pressure or wheel speed data being received by the TBCM over GMLAN serial data.


The loss of serial data brake pressure diagnostic is to determine whether or not there is a fault with the brake pressure data being received over GMLAN. This diagnostic looks at the brake pressure signal validity and protection value signals over a period of time to determine the fault state of the brake pressure sensor.


The loss of serial data wheel speed diagnostic is to determine whether or not there is a fault with the wheel speed data being received over GMLAN. This diagnostic looks at the wheel speed signal validity and sequence number errors over a period of time to determine the fault state


Conditions for Running the DTC

* Ignition ON.
* Ignition voltage is 9.5-17 volts.



Conditions for Setting the DTC

* The EBCM diagnoses a fault condition in the master cylinder pressure sensor, and sends a serial data message to the TBCM.
* The EBCM diagnoses a fault condition in the wheel speed sensors, and sends a serial data message to the TBCM.
* The TBCM losses communication with the EBCM.



Action Taken When the DTC Sets

* The trailer brake control will be disabled 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 ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

Trailer Brake Controls Description and Operation (Trailer Brake Controls Description and Operation)
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

1. Verify that DTC U0100, U0121, U0140, or U2099 are not set.

• If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) .

2. Verify that DTC C0035, C0040, C0045, C0050, OR C0131 are not set.

• If any of the DTCs are set, refer to Diagnostic Trouble Code (DTC) List - Vehicle (Diagnostic Trouble Code Descriptions) .

3. Replace the TBCM.



Repair Instructions

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


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