C0161

DTC C0161

Diagnostic Instructions

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



DTC Descriptor
DTC C0161 00
- TCS Brake Switch Circuit




Diagnostic Fault Information






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 3 circuits: a 10-volt reference circuit, a low reference circuit and a brake apply sensor signal circuit. The BCM supplies the 10-volt reference to the BPPS. Varying the level of application of the brake pedal changes the BPPS voltage range from less than 1 volt to greater than 9 volts through the BPPS signal circuit. When the conditions for running this DTC are met, the BCM will use the brake fluid pressure sensor to determine if the predicted operating range of the BPPS voltage is correct. If the BCM detects the BPPS voltage is out of the predicted range, the BCM will send a class 2 message to the EBCM to set DTC C0161. The EBCM will set a DTC C0131 or C0132 for a brake fluid pressure sensor fault. The BCM will set DTC C0277, C0278, or C0283, and C0870.


Conditions for Running the DTC

* The ignition is ON.
* The DTC can be set after system initialization.
* The ignition voltage is greater than 9 volts.



Conditions for Setting the DTC

* The BCM detects a failure in the BPPS system.
* 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 and ABS indicators turn ON.
* The driver information center (DIC) displays Service Stability System message.
* A malfunction DTC will set.



Conditions for Clearing the DTC

* The condition for the DTC is no longer present and the DTC is cleared with a scan tool.
* The EBCM automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles.



Diagnostic Aids

The DTC C0161 can be set if the vehicle has been driven with the brake applied during acceleration.


Reference Information
Schematic Reference

Antilock Brake System Schematics ([1][2]Antilock Brakes / Traction Control Systems)
Connector End View Reference

Component Connector End Views (Connector Views)
Description and Operation

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

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)



Scan Tool Reference

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


Circuit/System Verification

1. Verify that DTC C0277, C0297, or B3445 is not set.

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

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 BPMV and verify DTC does not reset. If DTC reset, replace the EBCM.