GM Service Manual Online
For 1990-2009 cars only

Diagnostic Fault Information

Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

Circuit/System Description

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

Reference Information

Schematic Reference

Brake Warning System Schematics

Connector End View Reference

Computer/Integrating Systems Connector End Views

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 OFF. Verify brake lamp turns OFF.
  2. If the brake lamp does not turn OFF, replace the IPC.
  3. Disconnect the park brake switch, with a scan tool observe park brake switch parameter. Verify parameter is reading ON.
  4. If parameter is OFF, replace the park brake switch
  5. Test the signal circuit of the park brake switch for a short to ground. Verify no short is found.
  6. If short is found repair circuit.
  7. Replace the BCM.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

    •  Parking Brake Indicator Switch Replacement
    •  Control Module References for IPC replacement, setup, and programming