Gremlins

Been trolling these forums since i picked up my 1991 4.0 A/T XJ Laredo back in November. Have been pretty happy overall and using the search I've found a lot of help with several minor problems over the last few months. You guys know your stuff! Unfortunately this latest issue has me stumped.

Here's where we are today: Jeep has been running fine, getting me to work and back on a regular basis. One evening, I walk out to find it won't start - dead battery.

Roll my pickup alongside for a jump and when i hook up i find the headlights stuck in hi-beam, the alarm going off (lights flash but the horns never go) and the wipers wagging back and forth. Not good.

disable the alarm and try to get it to turn over with the jumpers on and get no love. Not enough juice with the battery stone dead and the headlights and wipers going. Roll out the trickle charger, disconnect the battery from the vehicle and hook it up for a charge over night.

Next morning, a wiggle of the hi-beam stick dislodges the hi-beam control and I re-connect the battery to find that this time the jeep will start. Headlights no longer stuck on, wipers no longer running. For about 2 minutes it runs and then dies. Battery dead again!

Further investigation shows: blown "dome light" fuse and a blown "Gauges" fuse under dash and 2 blown 60A alternator fuses under the hood. This explains the failure to run for more than a few minutes - no alternator juice to the battery.

Replaced all blown fuses and troubleshooting continues:
-with the new alternator fuses and another charger session, the jeep starts and charges. This is good.
-Dome lights, blinkers, headlights, wipers all function as normal.
-Gauge cluster is now dead. A second check shows gauge fuse blown again.
-a third replaced gauge fuse (i know, i know) also pops.
- Cruise control never worked anyways.

OK, a short in the gauge circuit, right? My wiring diagram shows that this fuse powers the Cruise Control, the Alarm module and the instrument cluster.

Disconnected the cruise control switch, new fuse = smoke
Disconnected the alarm module, new fuse = smoke and no start (ignition cutoff?)
Disconnected the wiper module, new fuse = smoke.

With the fuse removed and measure from the fuse block, the gauge circuit reads ~ 70ohms to ground. Doesn't seem to be dead shorted.

I'm at a loss at this point. I had assumed that something in the hi-beam/wiper/blinker circuit was shorted when the control got stuck but isolating these circuits doesn't seem to indicate that this was the case. Any ideas? Sorry to be long winded, the jeep runs but i rely on those gauges to keep this 230k old girl running in the sweet spot!

Thanks in advance for taking the time to help!

-b

first suspect would be alarm, factory? or aftermarket? without any experience, all i would say is eliminate EACH problem circuit one at a time. or, disconnect ALL of them and see if any one will work without the others. thats the best i got as electricity is to me what kryptonite is to superman...

can't visualize your problem however ignition cylinder failure is leading cause of these types of problems, headlight switch failure is second

Ignition switch seems likely to me as well. Alarm is factory. Seems to work with exception that horn doesn't sound when it goes off. Have tried disconnecting each circuit mentioned above individually and still keep popping the fuse. Trying to avoid pulling the cluster but it may come to that if ignition switch doesn't do it. Thanks for the input!

Replaced ignition switch and still blow 'gauges' fuse every time I put power to it.

Tried the following as a next step:

Disconnected Wiper Module
Disconnected Dimmer Switch
Disconnected / removed Instrument Panel
Disconnected Cruise Control Module
Disconnected Alarm Module
Turned on power (with brand new ignition switch) and immediately popped the "Gauges" fuse.

I guess this means it's a short in the wiring somewhere? Am I missing something?