Trailer Brake Controls

DTC C0561

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 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.

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.
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.
3. Replace the TBCM.