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 00

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Antilock Brake System (ABS) Brake Switch Circuit

Circuit/System Description

The brake pedal position (BPP) sensor is an input to the body control module (BCM). The BCM activates the brake lamps when the BPP is in an applied state. The BCM then sends a brake pedal applied state status via high speed GMLAN serial data messages to the electronic brake control module (EBCM). The brake pressure modulator valve (BPMV) sensor monitors the brake pressure and sends a variable voltage signal to the EBCM.

Conditions for Running the DTC

* The vehicle speed is greater than 16 km/h (10 mph).

* The ignition voltage is greater than 9.5 volts.

Conditions for Setting the DTC

* The EBCM detects the vehicle speed greater than 21 km/h (13 mph), the brake pedal is Applied for 1 minute, and brake pressure is not increasing.

* The EBCM detects the brake pedal is Released and the vehicle speed is decreasing while brake pressure is increasing.

Action Taken When the DTC Sets

* The EBCM disables the antilock brake system (ABS), traction control system (TCS) and vehicle stability enhancement system (VSES) 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 100 consecutive drive cycles.

Diagnostic Aids

The DTC C0161 00 can be set if the brake pedal is applied while accelerating, the brake pedal position sensor is out of adjustment, or the pedal is binding causing residual brake pressure to be detected, without the brake light signal detected.

Reference Information

Schematic Reference

Antilock Brake System Schematics [1][2]Antilock Brakes / Traction Control Systems

Connector End View Reference

Component Connector End Views A/C Compressor Clutch

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 Control Module References 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 C0297 is not set.

• If DTC is set, refer to Diagnostic Trouble Code (DTC) List - Vehicle Diagnostic Trouble Code (DTC) List - Vehicle.

2. Apply and release the brake pedal. Verify brake lamps operate properly.

• If brake lamps do not operate properly, refer to Symptoms - Lighting Symptoms - Lighting.

3. Verify the brake pedal position sensor or the brake pedal is not binding causing residual brake pressure to be detected, while the brake lights operate properly.

• If a condition is found, repair or replace the applicable component.

4. Replace the brake pressure modulator valve assembly (BPMV). Verify DTC does not reset. If DTC resets, replace the EBCM.

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 Control Module References for EBCM replacement, programming and setup