Circuit/System Testing

Brake Warning Indicator Inoperative when Park Brake is Applied 

1. Ignition ON. With the scan tool, select Instrument Panel Cluster, Special Functions, Display Test. Command the instrument panel lamps ON. Verify that the brake warning indicator turns ON.
   • If the brake warning indicator does not turn ON, replace the IPC.
2. Disconnect the park brake switch. Connect a 3 amp fused jumper wire between the signal circuit terminal A of the park brake switch and ground. Ignition ON, Verify that the brake warning indicator is OFF.
   • If the brake warning indicator turns ON, replace the park brake switch.
3. Test the signal circuit for continuity. Verify that the signal circuit does not have a high resistance or an open.
   • If a high resistance or an open is found, repair the circuit.
4. Replace the IPM.

Brake Warning Indicator Inoperative when Brake Fluid is Low 

1. Ignition ON. With the scan tool, select Instrument Panel Cluster, Special Functions, Display Test. Command the instrument panel lamps ON. Verify that the brake warning indicator turns ON.
   • If the brake warning indicator does not turn ON, replace the IPC.
2. Disconnect the brake fluid level switch. Connect a 3 amp fused jumper wire between the signal circuit terminal A and the ground circuit terminal B of the brake fluid level switch. Ignition ON, Verify that the brake warning indicator is OFF.
   • If the brake warning indicator turns ON, replace the brake fluid level switch.
3. Test the signal circuit and the ground circuit for continuity. Verify that the signal circuit and the ground circuit does not have a high resistance or an open.
   • If a high resistance or an open is found, repair the circuit.
4. Replace the IPC.

Brake Warning Indicator Always On 

1. Engine running. Observe the driver information center (DIC). Verify that the CHECK BRAKE FLUID message is not displayed on the DIC.
   • If the CHECK BRAKE FLUID message is displayed on the DIC, go to Circuit/System Testing: CHECK BRAKE FLUID Message and Brake Warning Indicator Always On.
2. Ignition ON. With the scan tool, select Instrument Panel Cluster, Special Functions, Display Test. Command the instrument panel lamps OFF. Verify that the brake warning indicator turns OFF.
   • If the brake warning indicator does not turn OFF, replace the IPC.
3. Disconnect the park brake switch connector. With a scan tool, observe the Parking Brake Switch parameter in the Instrument Panel Module Inputs data display. Verify that the scan tool Parking Brake Switch parameter is Applied.
   • If the scan tool Parking Brake Switch parameter is Released, replace the park brake switch.
4. Test the park brake switch signal circuit for a short to ground. Verify that the park brake switch signal circuit is not shorted to ground.
   • If the park brake switch signal circuit is shorted to ground, repair the circuit.
5. Replace the IPM.

CHECK BRAKE FLUID Message and Brake Warning Indicator Always On 

1. Inspect the master cylinder reservoir for the proper brake fluid level.
   • If brake fluid level is low, refer to Hydraulic Brake System Diagnosis  .
2. Ignition ON. With the scan tool, select Instrument Panel Cluster, Special Functions, Display Test. Command the instrument panel lamps OFF. Verify that the brake warning indicator turns OFF.
   • If the brake warning indicator does not turn OFF, replace the IPC.
3. Disconnect the brake fluid level switch connector. With a scan tool, observe the Brake Fluid parameter in the Instrument Panel Cluster data display. Verify that the scan tool Brake Fluid parameter is Low.
   • If the scan tool Brake Fluid parameter is OK, replace the brake fluid level switch.
4. Test the brake fluid level sensor signal circuit for a short to ground. Verify that the brake fluid level sensor signal circuit is not shorted to ground.
   • If the brake fluid level sensor signal circuit is shorted to ground, repair the circuit.
5. Replace the IPC.