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 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.

### Conditions for Running the DTC

The ignition voltage is greater than 9.5 volts.

### Conditions for Setting the DTC

• | The vehicle speed is greater than 40 km/h (25 mph) and then slow down to less than 3 Km/h (2 mph) 4 times and the brake pedal signal does not show any change in state.

• | The vehicles speed is greater than 20 Km/h (12 mph) and the brake pedal signal indicates an active state for continuously more than 6 minutes.

• | The brake pressure signal indicates pressure increase but the brake pedal position signal is not changing.

### Action Taken When the DTC Sets

The ABS/TCS remains functional.

### Conditions for Clearing the DTC

• | The condition for the DTC is no longer present.

• | 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 brake is applied when driving the vehicle.

### 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 Verification

1. Ignition ON, observe the scan tool EBCM BPP parameter. The reading should be Released and change to Applied with the brake pedal pressed.
2. Verify that DTC C0277 is not set.

⇒ | If DTC is set, refer to DTC C0277 or C0890 .

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.