For 1990-2009 cars

### Circuit Description

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

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0161 ABS/TCS Brake Switch Circuit Malfunction

This vehicle has DTCs which include DTC Symptoms. For more information on DTC Symptoms, refer to DTC Symptom Description.

Symptom Type | Symptom Type Descriptor
--- | ---
11 | Above Maximum Threshold
12 | Below Minimum Threshold

### Conditions for Running the DTC

#### C0161 11

• | The ignition switch is turned ON.

• | Vehicle speed is greater than 16 km/h (10 mph).

• | The ignition voltage is greater than 8 volts.

#### C0161 12

• | The ignition is turned ON.

• | The ignition voltage is greater than 8 volts.

### Conditions for Setting the DTC

#### C0161 11

• | The brake pedal is sensed as applied.

• | Vehicle speed is greater than 40 km/h (25 mph).

• | The vehicle acceleration is greater than 8 km/h/second (5 mph/second).

#### C0161 12

• | The brake pedal is not applied.

• | The master cylinder pressure is greater than 150 psi.

• | The vehicle speed is greater than 24 km/h (14 mph).

• | The vehicle deceleration is greater than 11.5 km/h/second (7 mph per second).

### Action Taken When the DTC Sets

If equipped, the following actions occur:

• | The EBCM disables the engine drag control (EDC)/tire pressure monitor (TPM)/vehicle stability enhancement system (VSES) for the duration of the ignition cycle.

• | Traction control system (TCS) is degraded.

• | The traction control and active handling indicator turns ON.

• | The driver information center (DIC) displays the following messages:

- | Service Traction Control System

- | Service Vehicle Stability System

• | The antilock brake system (ABS) remains functional.

### 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

When running the vehicle and apply the brake at decelerating, DTC C0161 11 will set.

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step checks if there is other DTCs that can cause the BPS failure.

2. This step checks to see if the DTC will reset as current.

Step | Action | Yes | No
--- | --- | --- | ---
Schematic Reference: Exterior Lights Schematics Connector End View Reference: Lighting Systems Connector End Views and Computer/Integratig Systems Connector End Views .
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Use the scan tool to display DTCs for the body control module (BCM). Does the scan tool display DTC C0277 or C0278? | Go to Diagnostic Trouble Code (DTC) List - Vehicle | Go to Step 3
3 |

1. Confirm that the brake pedal position (BPP) is adjusted to the correct position and perform the BPP calibration procedure. Refer to Brake Pedal Position Sensor Calibration .
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does DTC C0161 reset?

Go to Diagnostic Aids

Go to Step 4

4 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

Go to Step 2

System OK