Tracking down electrical problem

I have an electrical issue that's draining the battery when the XJ isn't running. Unfortunately, it's an intermittent problem, so I'm thinking it's likely due to wiring chaffing. I plan to check the wiring in the tilt steering first. I'm looking for advice from those who have had this sort of problem and what your experience was. What other areas do you think I should check? Thanks,

Tom

A couple of things you'd probably have noticed, but might not depending on where you park: short in interior light wiring, and brake light switch. I had the latter on a Chevy truck, very tricky because it would come on occasionally after I'd checked it.

Sporadic problems are a PITA to troubleshoot - I'd much rather work on a problem that's constant anyday.
Here's something I found in the automotive section of the popularmechanics.com website that may help:
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Dropped Out
My 1986 Olds Calais seems to drain power from its battery. I’ve had many mechanics check it out, and no one is able to find the problem. I’ve had the alternator and battery replaced. Some have suggested rust in the connections. It will be fine for a while, and then one morning the battery is dead.
MIKE H.
VIA INTERNET

We have to assume that the mechanics who installed the alternator and battery did so properly. That means something is draining your battery overnight. Start by getting an ammeter capable of reading 10 to 20 amps—beyond the abilities of your trusty multimeter. Pull the wire from the solenoid to the starter so you don’t accidentally try to start the motor and fry even the 20-amp ammeter. Put the ammeter in series with the battery’s positive terminal. The current across the meter should be below 100 milliamps (ma) or so. The car’s computer, radio and clock will draw a very small amount of current to keep their memory. They’ll take months to discharge the battery. But a total discharge, like you’re seeing overnight, requires at least 500 ma, or more like 1 to 2 amps. Start pulling fuses from the fuse box one at a time until you find the offending circuit. Now it’s just a matter of figuring what’s staying on. Odds are a glovebox or trunk light switch is stuck. Aftermarket alarm systems are notorious for sucking batteries. You’ll just have to systematically subdivide the electrical system until you find where the current is going.

I don´t know for sure if the 92 wiring runs the same way, as the post 90´s. But I had the same issues, with the wifes 87. Under the drivers side carpet, interior lights and some other stuff. The tape came loose on the cable bunch, it spread over the floor, was chaffed and oxidized (green) the splices were also green. Repaired everything (solder, tape) covered it with a pastic cable harness cover. Moved it as far left as possible.
Hood trouble light stays on. Glove box switch broken. Door switches corroded, make enough contact through moisture to drain battery, but not enough to light bulbs (or very dim). Dirty battery, usually open type, the battery is covered in a layed of dirt, moisture and acid salts.
Could be any constant power wire, usually at the connector, green stuff, is a poor conductor, but still a conductor.

Also check electric locks, if so equipped. They can stick intermittently. Sounds like it has to be something that is always powered up with the key off.

Do you have a courtesy light over the passenger sunvisor? If so, check it. I had one staying on and draining the battery in a Mustang. It was very hard to find, since the light didn't show with the sunvisor turned up.

Thanks for the responses. Just to emphasize, it's intermittent. Usually it will last a week....I go out in the morning to start it and it barely turns over (thankfully I have an Optima battery). Then the next week, it has full power and cranks right up. The only thing I mess with that might move wires is the tilt steering, which I adjust when I pull my wallet out to show my ID at a secure entry point.

Tom

Further to what RTicUL8 said....

Connect meter as stated.

Since your problem is intermittent, the shaking of harnesses, the wacking of panels, courtesy lights, tilting str col, etc. is probably your method of isolation.

Shake and whack until you see a significant changes in current drain.

(you will need to rig-up long probes for the meter -- so you can move it around to different areas of the vehicle .)

Had a flakey switch on my rear deck. Drove me crazy for a bit.

Good luck,
Jay in MA

I have fixed a similar problem on two Cherokees an 87 and a 92. After doing the current measuring and fuse pulling routine, the drain didn't go away (150 mA). What I found was that one of the diodes in the alternator leaked. Swapping out the alternators fixed both jeeps.