C0161

DTC C0161

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Diagnostic System Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Strategy Based Diagnosis) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Diagnostic Procedure Instructions) provides an overview of each diagnostic category.

DTC Descriptor
DTC C0161 5A
- Antilock Brake System (ABS) Brake Switch Circuit Plausibility Failure

Circuit/System Description

The electronic brake control module (EBCM) detects inputs from the brake pressure sensor, vehicle speed, and a serial data message from the body control module (BCM) that the brake pedal is applied. When the vehicle is stopping the EBCM monitors for the brake pedal is pressed, with the brake pressure increasing and the vehicle is slowing down, or when the vehicle is accelerating, the brake pedal is not pressed and brake pressure is not increasing.

Conditions for Running the DTC

* Ignition ON.
* Ignition voltage is greater than 10 volts.

Conditions for Setting the DTC

* The EBCM detects the vehicle speed greater than 8 km/h (5 mph), the brake pedal is Applied for 1 minute , and brake pressure is not increasing.
* The EBCM detects brake pedal is Released and the vehicle speed is decreasing while the brake pressure is increasing.

Actions Taken when the DTC Sets

* The EBCM disables the traction control and StabiliTrak for the duration of the ignition cycle.
* A driver information center message and/or a warning indicator may be displayed.

Conditions for Clearing the DTC

* The condition for the DTC is no longer present.
* The EBCM clears the history DTC when a current DTC is not detected in 40 consecutive drive cycles.

Diagnostic Aids

The DTC C0161 5A can be set if the brake pedal is applied while accelerating.

Reference Information
Schematic Reference

Antilock Brake System Schematics (Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector End Views By Name)
Description and Operation

ABS Description and Operation (Description and Operation)
Electrical Information Reference

* Circuit Testing (Circuit Testing)
* Connector Repairs (Connector Repairs)
* Testing for Intermittent Conditions and Poor Connections (Testing for Intermittent Conditions and Poor Connections)
* Wiring Repairs (Wiring Repairs)

Scan Tool Reference

Control Module References (Programming and Relearning) for scan tool information

Circuit/System Verification

Note: Diagnose all other brake light DTCs or Symptoms prior to performing this diagnostic procedure.

1. Verify that DTC C0277 or C0278 is not set.

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

2. Ignition ON, observe the scan tool EBCM BPP parameter while applying and releasing the brake pedal. The reading should change between Applied and Released.

• If the parameter does not change between applied and release, replace the EBCM.

3. Replace the brake pressure modulator valve assembly.

Repair Instructions

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

* Brake Pressure Modulator Valve Replacement (Brake Pressure Modulator Valve Replacement)
* Control Module References (Programming and Relearning) for EBCM replacement, setup, and programming