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