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.

### Circuit/System Description

The body control module (BCM) sees the park brake switch and brake fluid level switch input to grounded and illuminates the red brake indicator. The BCM sees the park brake switch input grounded, it sends a serial data message to the IPC requesting illumination of the red brake indicator.

### Reference Information

#### Schematic Reference

Hydraulic Brake Schematics

#### Connector End View Reference

Hydraulic Brake Connector End Views

#### Description and Operation

Brake Warning System 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

### Circuit/System Testing

1. With the scan tool, select instrument panel special functions Lamp Test. Command the instrument panel lamps ON. Verify brake lamp turns ON.

⇒ | If the brake lamp does not turn ON, replace the IPC.

2. Release the park brake. Disconnect the brake fluid level switch. Connect a 3-amp jumper wire between the signal circuit of the brake fluid level switch and the ground circuit of the brake fluid level switch. Ignition ON, verify the brake lamp is ON.

⇒ | If the brake lamp does not turn ON, test the signal circuit and ground circuit for a high resistance/open or replace the brake fluid level switch.

3. Disconnect the park brake switch. Connect a 3-amp jumper wire between signal circuit of the park brake switch and ground. Ignition ON, verify the brake lamp is ON.

⇒ | If the brake lamp does not turn ON, test the signal circuit high resistance/open or replace the BCM.

4. Replace the park brake switch.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Brake Fluid Level Indicator Switch Replacement

• | Parking Brake Indicator Switch Replacement

• | Control Module References for BCM and IPC replacement, setup, and programming