Brake Warning Indicator Malfunction

Brake Warning Indicator Malfunction

Diagnostic Instructions

* Perform the Diagnostic System Check - Vehicle (Initial Inspection and Diagnostic Overview) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (Initial Inspection and Diagnostic Overview) for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions (Initial Inspection and Diagnostic Overview) provides an overview of each diagnostic category.



Diagnostic Fault Information






Circuit/System Description

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


Diagnostic Aids

Inspect the master cylinder reservoir for the proper brake fluid level.

If brake fluid level is low, refer to Hydraulic Brake System Diagnosis (Component Tests and General Diagnostics) .



Reference Information
Schematic Reference

Hydraulic Brake Schematics ([1][2]Electrical Diagrams)
Connector End View Reference

Component Connector End Views (Connector Views)
Electrical Information Reference

* Circuit Testing (Component Tests and General Diagnostics)
* Connector Repairs (Component Tests and General Diagnostics)
* Testing for Intermittent Conditions and Poor Connections (Component Tests and General Diagnostics)
* Wiring Repairs (Component Tests and General Diagnostics)

Scan Tool Reference

Control Module References (Programming and Relearning)for Scan Tool Information


Circuit/System Verification

With a scan tool, select instrument panel special functions Displays Test. Command the instrument panel lamps OFF. Verify the IPC brake lamp indicator turns off. If the IPC brake lamp indicator does not turn off check the circuit testing Brake Warning Indicator Always On.


With a scan tool, select instrument panel special functions Displays Test. Command the instrument panel lamps ON. Verify the IPC brake lamp indicator turns on. If the IPC brake lamp indicator does not turn on check the circuit testing Brake Warning Indicator Inoperative.


Circuit/System Testing
Brake Warning Indicator Inoperative

1. 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.

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.


Brake Warning Indicator Always On

1. 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.

2. 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.

3. Test the park brake switch signal circuit for a short to ground. Verify no short is found.

• If short is found, repair the circuit.

4. Replace the BCM.



Repair Instructions

Perform the Diagnostic Repair Verification (Verification Tests) after completing the diagnostic procedure.

* Brake Fluid Level Indicator Switch Replacement (Service and Repair)
* Parking Brake Indicator Switch Replacement (Service and Repair)
* Control Module References (Programming and Relearning)for BCM and IPC replacement, setup, and programming