Brake warning lamp. Cluster illumination lamp

Brake warning lamp

The diagnosis found here addresses an inoperative brake warning lamp condition. If the brake warning lamp stays on with the ignition switch in the On position and the park brake released, or comes on while driving, refer to Rear Wheel Antilock for vehicles equipped with a rear wheel anti-lock brake system, or refer to Antilock Brakes for vehicles equipped with a four wheel anti-lock brake system in the Diagnosis and Testing section of Group 5 - Brakes for further diagnosis. If no brake system problem is found, the following procedure will help locate a faulty park brake switch or park brake switch sense circuit. For complete circuit diagrams, refer to Instrument Cluster in the Contents of Group 8W - Wiring Diagrams.

(1) Check the fused ignition switch output (run/ start) fuse in the junction block. If OK, go to Step 2.

If not OK, repair the shorted circuit or component as required and replace the faulty fuse.

(2) Turn the ignition switch to the On position.

Check for battery voltage at the fused ignition switch output (run/start) fuse in the junction block. If OK, go to Step 3. If not OK, repair the open fused ignition switch output (run/start) circuit to the ignition switch as required.

(3) Turn the ignition switch to the Off position.

Disconnect and isolate the battery negative cable.

Disconnect the wire harness connector at the park brake switch. With the park brake released, check for continuity between the park brake switch terminal and a good ground. There should be no continuity. If OK, go to Step 4. If not OK, adjust or replace the faulty park brake switch.

(4) Remove the instrument cluster. With the park brake switch wire harness connector still disconnected, check for continuity between the park brake switch sense circuit cavity of the park brake switch wire harness connector and a good ground. There should be no continuity. If OK, go to Step 5. If not OK, repair the shorted park brake switch sense circuit as required.

(5) Check for continuity between the park brake switch sense circuit cavities of the instrument cluster wire harness connector A and the park brake switch wire harness connector. There should be continuity. If OK, refer to Instrument Cluster - Preliminary Diagnosis in the Diagnosis and Testing section of this group for further testing of the brake warning lamp and the instrument cluster circuitry. If not OK, repair the open park brake switch sense circuit as required.

Cluster illumination lamp

The diagnosis found here addresses an inoperative instrument cluster illumination lamp condition. If the problem being diagnosed includes inoperative exterior lighting controlled by the headlamp switch, that system needs to be repaired first. If the exterior lamps controlled by the headlamp switch are inoperative, refer to Headlamp Diagnosis in the Diagnosis and Testing section of Group 8L - Lamps for diagnosis. If no exterior lighting system problems are found, the following procedure will help locate a short or open in the cluster illumination lamp circuit.

If the problem being diagnosed involves a lack of dimming control for the odometer/trip odometer Vacuum Fluorescent Display (VFD), but all of the other cluster illumination lamps can be dimmed, repair the open headlamp switch output circuit input to the instrument cluster. For complete circuit diagrams, refer to Instrument Cluster in the Contents of Group 8W - Wiring Diagrams.

(1) Check the panel lamps dimmer fuse in the junction block. If OK, go to Step 2. If not OK, repair the shorted circuit or component as required and replace the faulty fuse.

(2) Turn the park lamps on with the headlamp switch. Rotate the panel lamps dimmer thumbwheel on the headlamp switch upward to just before the interior lamps detent. Check for battery voltage at the panel lamps dimmer fuse in the junction block.

Rotate the panel lamps dimmer thumbwheel downward while observing the test voltmeter. The reading should go from battery voltage to zero volts. If OK, go to Step 3. If not OK, repair the open panel lamps dimmer switch signal circuit to the headlamp switch as required. If the circuit tests OK, refer to Headlamp Diagnosis in the Diagnosis and Testing section of Group 8L - Lamps to diagnose the headlamp switch.

(3) Disconnect and isolate the battery negative cable. Remove the instrument cluster. Turn the headlamp switch off. Remove the panel lamps dimmer fuse from the junction block. Probe the fused panel lamps dimmer switch signal circuit cavity of the instrument cluster wire harness connector B. Check for continuity to a good ground. There should be no continuity. If OK, go to Step 4. If not OK, repair the shorted fused panel lamps dimmer switch signal circuit as required.

(4) Install the panel lamps dimmer fuse in the junction block. Connect the battery negative cable.

Turn the park lamps on with the headlamp switch.

Rotate the panel lamps dimmer thumbwheel on the headlamp switch upward to just before the interior lamps detent. Check for battery voltage at the fused panel lamps dimmer switch signal circuit cavity of the instrument cluster wire harness connector B. If OK, replace the faulty cluster illumination lamp bulb(s) and bulb holder(s). If not OK, repair the open fused panel lamps dimmer switch signal circuit as required.