For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using the 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: ABS/TCS Brake Switch Circuit Signal Malfunction

### Circuit/System Description

The BCM illuminates the stop lamps by applying battery positive voltage to the stop lamp supply voltage circuit. The electronic brake control module (EBCM) receives a voltage input from the stop lamp supply voltage circuit to determine if the brake pedal is applied.

### Conditions for Running the DTC

• | The ignition is ON.

• | The vehicle speed is greater than 20 km/h (12 mph).

• | The ignition voltage is greater than 9.5 volts.

### Conditions for Setting the DTC

• | The brake pedal is sensed as applied for 6 minutes.

• | The vehicle speed is greater than 20 km/h (12 mph).

• | The EBCM does not receive a signal change from the stop lamp supply voltage circuit.

• | Vehicle speed exceeds 40 km/h (25 mph) in four cycles, and decelerates to under 3 km/h (2 mph).

### Action Taken When the DTC Sets

The 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

The DTC C0161 00 can be set if the vehicle has been driven with the brake applied during acceleration. Also inspect the brake pedal switch and connector for proper operation.

### Reference Information

#### 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 body control module (BCM).

⇒ | If B codes are present, go to Diagnostic System Check - Vehicle .

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

### Repair Verification

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.