For 1990-2009 cars

### 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: Antilock Brake System (ABS) Brake Switch/Sensor Circuit not Plausible.

### 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 instrument panel module (IPM) supplies the 5-volt reference to the BPP.

### Conditions for Running the DTC

• | The ignition is ON.

• | 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 brake pedal is sensed as applied.

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

• | The vehicles acceleration exceeds 8 km/h per second (5 mph per second).

• | Brake pedal is not applied.

• | Master cylinder pressure is greater than 150 psi.

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

• | The vehicles deceleration exceeds 11.5 km/h per second (7 mph per second).

### Action Taken When the DTC Sets

The ABS/TCS/ESC 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

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

Antilock Brake System Connector End Views

#### Description and Operation Reference

ABS Description and Operation

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Scan Tool Data List for EBCM

### Circuit/System Verification

With the ignition ON, use a scan tool to display DTCs for the BCM.

⇒ | If DTC C0277 or C0278 are present, go to Diagnostic System Check - Vehicle .

⇒ | If no DTCs are present, go to Diagnostic Aids.

### Repair Verification

Diagnostic Repair Verification