Wrangler L4-2.5L VIN P (1999)
Four-Wheel Drive (4WD) Indicator Lamp: Testing and Inspection
HARD WIRED LAMP DIAGNOSIS
Each of the lamps depends upon a hard wired circuit input to the instrument cluster for proper operation. The following procedures will help to
diagnose conditions that may cause an inoperative hard wired lamp circuit condition.
WARNING: ON VEHICLES EQUIPPED WITH AIR-BAGS, REFER TO AIRBAG AND SEAT BELTS/AIR BAGS BEFORE
ATTEMPTING ANY STEERING WHEEL, STEERING COLUMN, OR INSTRUMENT PANEL COMPONENT DIAGNOSIS OR
SERVICE. FAILURE TO TAKE THE PROPER PRECAUTIONS COULD RESULT IN ACCIDENTAL AIR-BAG DEPLOYMENT AND
POSSIBLE PERSONAL INJURY.
The diagnosis found here addresses an inoperative four-wheel drive indicator lamp condition. If the problem being diagnosed is related to lamp
accuracy, be certain to confirm that the problem is with the lamp or switch and not with a damaged or inoperative transfer case or transfer case
linkage. If no transfer case problem is found, the following procedure will help locate a short or open in the indicator lamp circuit.
1. Check the fused ignition switch output (run/ start) fuse in the fuseblock module. 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 fuseblock module. 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 transfer case switch wire harness
connector. Check for continuity between the ground circuit cavity of the transfer case switch wire harness connector and a good ground. There
should be continuity. If OK, go to Step 4. If not OK, repair the open ground circuit to ground as required.
4. Connect the battery negative cable. Turn the ignition switch to the On position. Install a jumper wire between the part time four wheel drive
indicator lamp driver circuit cavity of the transfer case switch wire harness connector and a good ground. The four- wheel drive indicator lamp
should light. If OK, replace the faulty transfer case switch. If not OK, go to Step 5.
5. Turn the ignition switch to the Off position. Disconnect and isolate the battery negative cable. Remove the instrument cluster. With the transfer
case switch wire harness connector still disconnected, check for continuity between the part time four wheel drive indicator lamp driver circuit
cavity of the instrument cluster wire harness connector B and a good ground. There should be no continuity If OK, go to Step 6. If not OK, repair
the shorted part time four wheel drive indicator lamp driver circuit as required.
6. Check for continuity between the part time four wheel drive indicator lamp driver circuit cavities of the instrument cluster wire harness connector
B and the transfer case switch wire harness connector. There should be continuity. If OK, replace the faulty bulb. If not OK, repair the open part
time four wheel drive indicator lamp driver circuit as required.