Circuit/System Testing: Notes

WARNING: This page is about a different car, the 2008 Buick LaCrosse and 2008 Buick Allure. However, it is still accessible from the selected car via links, so may be relevant.

Brake Warning Indicator Inoperative

With the scan tool, select instrument panel special functions Displays Test. Command the instrument panel lamps ON. Verify brake lamp turns ON.
- If the brake lamp does not turn ON, replace the IPC.
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.
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.
Replace the park brake switch.

Brake Warning Indicator Always On

With the scan tool, select instrument panel special functions Lamp Test. Command the instrument panel lamps OFF. Verify brake lamp turns OFF.
- If the brake lamp does not turn OFF, replace the IPC.
Disconnect the park brake switch. With a scan tool, observe the Park Brake Switch parameter. Verify parameter is reading ON.
- If the parameter is OFF, replace the park brake switch.
Test the park brake switch signal circuit for a short to ground. Verify no short is found.
- If short is found, repair the circuit.
Replace the BCM.