Cluster Illumination Diagnosis

Cluster Illumination Diagnosis
The diagnosis found here addresses an inoperative instrument cluster illumination lamp condition.

If the problem being diagnosed is a single inoperative illumination lamp, be certain that the bulb and bulb holder unit are properly installed in the instrument cluster electronic circuit board. If no installation problems are found replace the faulty bulb and bulb holder unit.

If all of the cluster illumination lamps are inoperative and the problem being diagnosed includes inoperative exterior lighting controlled by the headlamp switch, that system needs to be repaired first.

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, test and repair the day brightness circuit between the instrument cluster and the headlamp switch as required. Refer to the appropriate wiring information. The wiring information includes wiring diagrams, proper wire and connector repair procedures, details of wire harness routing and retention, connector pin-out information and location views for the various wire harness connectors, splices and grounds.

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.

1. Check the instrument panel dimmer fuse (Fuse 5 - 5 ampere) in the Junction Block (JB).
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 exterior lamps ON with the headlamp switch. Rotate the headlamp switch panel lamps dimmer thumbwheel upward to just before the interior lamps detent. Check for battery voltage at the panel lamps dimmer fuse (Fuse 5 - 5 ampere) in the JB. 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 between the headlamp switch and the JB as required.

3. Turn the exterior lamps OFF. Disconnect and isolate the battery negative cable. Remove the instrument cluster. Remove the instrument panel dimmer fuse (Fuse 5 - 5 ampere) from the JB. Probe the fused panel lamps dimmer switch signal circuit cavity of the instrument panel wire harness connector (Connector C2) for the instrument cluster. 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 between the instrument cluster and the JB as required.

4. Reinstall the instrument panel dimmer fuse (Fuse 5 - 5 ampere) in the JB. Reconnect the battery negative cable. Turn the exterior lamps ON with the headlamp switch. Rotate the headlamp switch panel lamps dimmer thumbwheel 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 panel wire harness connector (Connector C2) for the instrument cluster.
If OK, replace the faulty bulb and bulb holder units.
If not OK, repair the open fused panel lamps dimmer switch signal circuit between the instrument cluster and the JB as required.