GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2009 🢒 Lucerne 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC C0161

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 C0161 00: TCS Brake Switch Circuit

Circuit/System Description

The brake pedal position (BPP) sensor is an input to the body control module (BCM). The BCM then sends a serial data message to the electronic brake control module (EBCM) and other electronic control modules. The BPP sensor is a potentiometer type sensor with a 5-volt reference circuit and a low reference circuit. The BCM supplies the 5-volt reference to the BPP.

Conditions for Running the DTC
    • Ignition ON.
    • The vehicle speed is greater than 16 km/h (10 mph).
    • The ignition voltage is greater than 8 volts.

Conditions for Setting the DTC
    • The brake pedal is sensed as applied during moderate to high vehicle acceleration.
    • With the vehicle decelerating, the brake pedal is sensed as released and the master cylinder pressure is greater than 90 psi.

Action Taken When the DTC Sets
    • The EBCM disables the traction control system (TCS) and vehicle stability enhancement system (VSES) for the duration of the ignition cycle.
    • The Traction Control indicator illuminates.
    • The driver information center (DIC) displays Service Stability System.
    • The ABS remains functional.

Conditions for Clearing the MIL/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 vehicle has been driven with the brake applied during acceleration.

Reference Information

Schematic Reference

Antilock Brake System Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

ABS Description and Operation

Electrical Information Reference

    •  Circuit Testing
    •  Connector Repairs
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification
  1. Verify that DTC C0277, C0297, or B3445 is not set.
    2. ⇒ If any of the DTCs are set, refer to 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.
    3. ⇒If the parameter does not change between applied and release, replace the BPMV and verify DTC does not reset. If DTC reset, replace the EBCM.

Repair Instructions

Perform the Diagnostic Repair Verificationafter completing the diagnostic procedure.

Control Module References for EBCM replacement, setup, and programming