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 Warning 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 Warning indicator.

Reference Information
Schematic Reference

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

Component Connector End Views (Connector Views)
Description and Operation

Brake Warning System Description and Operation (Brake Warning System Description and Operation)
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

1. Verify the park brake is released and the brake fluid is at or above the proper level.

• If low, refer to Brake Fluid Loss (Brake Fluid Loss).

2. Command the IPC display test with a scan tool, the warning indicator should turn ON then OFF.

• If the red brake warning indicator does not illuminate, replace the IPC.

3. Ignition ON, observe the scan tool BCM Park Brake Switch parameter while applying and releasing the park brake. The parameter should cycle between Released and Set.

• If the parameter does not cycle between the specified values, refer to Park Brake Switch Malfunction.

4. Observe the scan tool IPC Brake Fluid Level Switch parameter. The reading should be OFF.

• If not the specified value, refer to Brake Fluid Level Switch Malfunction.

Circuit/System Testing

Park Brake Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the park brake switch.
2. Ignition ON, verify the scan tool BCM Park Brake Switch parameter is Released.

• If not the specified value, test the signal circuit terminal A for a short to ground. If the circuit tests normal, replace the BCM.

3. Install a 3A fused jumper wire between the signal circuit terminal A and ground. Verify the scan tool BCM Park Brake Switch parameter is Set.

• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance.

4. If all circuits test normal, test or replace the park brake switch.

Brake Fluid Level Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the brake fluid level switch.
2. Test for less than 1 ohm between the ground circuit terminal A and ground.

• If greater than the specified range, test the ground circuit for an open/high resistance.

3. Ignition ON, verify the scan tool IPC Brake Fluid Level Switch parameter is OFF.

• If not the specified value, test the signal circuit for a short to ground. If the circuit tests normal, replace the IPC.

4. Install a 3A fused jumper wire between the signal circuit terminal B and ground. Verify the scan tool IPC Brake Fluid Level Switch parameter is ON.

• If not the specified value, test the signal circuit for a short to voltage or an open/high resistance. If the circuit tests normal, replace the IPC.

5. If all circuits test normal, test or replace the brake fluid level switch.

Component Testing

Park Brake Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the park brake switch.
2. Test for infinite resistance between the signal terminal A and ground with the park brake released.

• If less than the specified value, replace the park brake switch.

3. Test for less than 1 ohm between the signal terminal A and ground with the park brake applied.

• If greater than the specified range, replace the park brake switch.

Brake Fluid Level Switch Malfunction
1. Ignition OFF, disconnect the harness connector at the brake fluid level switch.
2. Test for infinite resistance between the ground terminal A and the signal terminal B.

• If less than the specified value, replace the brake fluid level switch.

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