Trailer Brake Controls
DTC C0561
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* 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
* The ignition switch is in the ON position.
* Ignition voltage is in the range of 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
One or more of the following actions may occur:
* The trailer brake control will be disabled for the remainder of the ignition cycle.
* Service Trailer Brake System will be displayed on the Driver Information Center (DIC).
Conditions for Clearing the DTC
* The condition for the DTC is no longer present.
* The TBCM automatically clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles.
Diagnostic Aids
If there are any DTCs set for GMLAN communication such as U0100, U0121, U0140, or U2099 or the antilock brake control system, diagnose them first before to resolve DTCs described in this section.
Check for Brake Pressure Sensor and/or Wheel Speed Sensor DTCs in EBCM. Follow EBCM circuit repair procedure. If no DTCs are found in EBCM check for ground differential between EBCM and TBCM, loose TBCM ground, loose GMLAN signal terminal pins at TBCM or source of electromagnetic interference that may result from installation of aftermarket equipment
Scan Tool Output Controls for TBCM
Repair Instructions
Perform the Diagnostic Repair Verification after completing the diagnostic procedure. Verification Tests
Refer to Programming and Relearning for TBCM setup and programming. Programming and Relearning