The instrument panel cluster (IPC) supplies 5 volts to the brake fluid level switch and closes when the fluid level is low. The IPC then illuminates the red brake warning indicator.The body control module (BCM) supplies ignition voltage to the park brake switch, when the park brake pedal is pressed the switch closes and the BCM sends a serial data message to the IPC to illuminate the red brake warning indicator.

Schematic Reference

Hydraulic Brake Schematics

Connector End View Reference

Hydraulic Brake Connector End Views

Description and Operation

Brake Warning System Description and Operation

Electrical Information Reference

Scan Tool Reference

Scan Tool Data List

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

⇒	If the brake fluid is not at the proper level, refer to Brake Fluid Loss .

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

⇒	If the red brake warning indicator does not turn OFF, 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 Applied and Release.

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

4. Verify the scan tool IPC Brake Fluid parameter is OK.

⇒	If the parameter does not cycle between the specified values, refer to Brake Fluid Level Switch Malfunction.

Park Brake Switch Malfunction

1. Ignition OFF, disconnect the harness connector at the park brake switch.
2. Ignition ON, test for ignition voltage between the signal circuit terminal A and ground.

⇒	If less than the specified range, test the signal circuit for a short to ground or open/high resistance. If the circuit tests normal, replace the BCM.

3. 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 2.0 ohms of resistance 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 parameter is OK.

⇒	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 parameter is Low.

⇒	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 the circuits test normal, test or replace the brake fluid level switch.

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 not the specified value, replace the park brake switch.

3. Test for less than 1 ohm between the signal circuit 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 at the brake fluid level switch.

⇒	If greater than the specified value, replace the brake fluid level switch.

3. Test for less than 4.0 ohms of resistance between the ground terminal and the signal terminal with the switch in the closed position.

⇒	If greater than the specified range, replace the brake fluid level switch.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.