Brake Warning Indicator: Testing and Inspection

The diagnosis found here addresses an inoperative brake indicator lamp condition. If there are problems with several indicator lamps in the instrument cluster, (Refer to INSTRUMENT CLUSTER - DIAGNOSIS AND TESTING). If the brake indicator lamp stays ON with the ignition switch in the ON position and the park brake released or comes ON while driving. If no brake system problem is found, the following procedures will help to locate a shorted or open circuit, or a faulty switch input.

WARNING: ON VEHICLES EQUIPPED WITH AIRBAGS, DISABLE THE AIRBAG SYSTEM BEFORE ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR SERVICE. DISCONNECT AND ISOLATE THE BATTERY NEGATIVE (GROUND) CABLE, THEN WAIT TWO MINUTES FOR THE AIRBAG SYSTEM CAPACITOR TO DISCHARGE BEFORE PERFORMING FURTHER DIAGNOSIS OR SERVICE. THIS IS THE ONLY SURE WAY TO DISABLE THE AIRBAG SYSTEM. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIRBAG DEPLOYMENT AND POSSIBLE PERSONAL INJURY.

Lamp Does Not Illuminate During Bulb Test, But Does When Park Brake Applied
1. Disconnect and isolate the battery negative cable. Disconnect the instrument panel wire harness connector (Connector C1) for the ignition switch from the ignition switch connector receptacle. Check for continuity between the ground circuit cavity of the instrument panel wire harness connector (Connector C1) for the ignition switch and a good ground. There should be continuity. If OK, go to Step 2. If not OK, repair the open ground circuit to ground (G108) as required.
2. Disconnect the headlamp and dash wire harness connector for the brake warning pressure switch from the brake warning pressure switch terminals. Check for continuity between the red brake warning indicator driver (G9) circuit cavities of the instrument panel wire harness connector (Connector C1) for the ignition switch and the headlamp and dash wire harness connector for the brake warning pressure switch. There should be continuity. If not OK, repair the open red brake warning indicator driver (G9) circuit between the ignition switch and the brake warning pressure switch as required.

Lamp Illuminates During Bulb Test, But Does Not When Park Brake Applied
1. Disconnect and isolate the battery negative cable. Disconnect the floor wire harness connector for the park brake switch from the park brake switch terminal. Apply the parking brake. Check for continuity between the park brake switch terminal and a good ground. There should be continuity. If OK, go to Step 2. If not OK, replace the faulty park brake switch.
2. Disconnect the headlamp and dash wire harness connector for the brake warning pressure switch from the brake warning pressure switch terminals. Check for continuity between the red brake warning indicator driver (G9) circuit cavities of the floor wire harness connector for the park brake switch and the headlamp and dash wire harness connector for the brake warning pressure switch. There should be continuity. If not OK, repair the open red brake warning indicator driver (G9) circuit between the park brake switch and the brake warning pressure switch as required.

Lamp Does Not Illuminate
1. Disconnect and isolate the battery negative cable. Remove the instrument cluster from the instrument panel. Apply the parking brake. Check for continuity between the red brake warning indicator driver circuit cavity of the instrument panel wire harness connector (Connector C1) for the instrument cluster and a good ground. There should be continuity. If OK, replace the faulty brake indicator lamp bulb. If not OK, go to Step 2.
2. Disconnect the headlamp and dash wire harness connector for the brake warning pressure switch from the brake warning pressure switch terminals. Check for continuity between the two terminals of the brake warning pressure switch. There should be continuity. If OK, go to Step 3. If not OK, replace the faulty brake warning pressure switch.
3. Check for continuity between the red brake warning indicator driver circuit (G99) cavities of the headlamp and dash wire harness connector for the brake warning pressure switch and the instrument panel wire harness connector (Connector C1) for the instrument cluster. There should be continuity. If OK, go to Step 4. If not OK, repair the open red brake warning indicator driver circuit (G99) between the brake warning pressure switch and the instrument cluster as required.
4. Apply the parking brake. Check for continuity between the red brake warning indicator driver circuit (G9) cavity of the headlamp and dash wire harness connector for the brake warning pressure switch and a good ground. If not OK, repair the open red brake warning indicator driver circuit (G9) between the brake warning pressure switch and the park brake switch as required.

Lamp Remains Illuminated - Brake System Checks OK
1. Disconnect and isolate the battery negative cable. Disconnect the headlamp and dash wire harness connector for the brake warning pressure switch from the brake warning pressure switch terminals. Check for continuity between the red brake warning indicator driver circuit (G99) cavity of the headlamp and dash wire harness connector for the brake warning pressure switch and a good ground. There should be no continuity. If OK, go to Step 2. If not OK, repair the shorted red brake warning indicator driver circuit (G99) between the brake warning pressure switch and the instrument cluster as required.
2. Check for continuity between the red brake warning indicator driver circuit (G9) cavity of the headlamp and dash wire harness connector for the brake warning pressure switch and a good ground. There should be no continuity. If OK, go to Step 3. If not OK, repair the shorted red brake warning indicator driver circuit (G9) between the brake warning pressure switch and the ignition switch or the park brake switch as required.
3. Check for continuity between each of the two terminals of the brake warning pressure switch and a good ground. In each case, there should be no continuity. If not OK, replace the faulty brake warning pressure switch.