Important: Always perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

The body control module (BCM) sends a serial data message to the instrument panel cluster (IPC) requesting illumination of the brake warning indicator when the park brake switch signal circuit is grounded.

Schematic Reference

Brake Warning System Schematics

Connector End View Reference

Computer/Integrating Systems Connector End Views

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

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

Important: Always perform the Diagnostic Repair Verification after completing the diagnostic procedure.