A short every few months leaving a dead battery in a 92 Explorer is so annoying my father in law, after taking it to mechanics, gave the car to my wife and got a newer Explorer.

Battery + goes to only 3 places: starter, relay, fusebox, only removing fusebox power cable cures short (trouble lights if I pull starter or relay cables, only unlights when I pull single cable to fusebox: short must be in or past fusebox.) I started pulling fuses to find the culprit but stil short with all fuses out. (I slid fusebox off bracket, one cable in, many wires out, one or more must be bypassing fuses.)
I couldn't see if any of those wires went to 3 relays but I pulled them, still short.

Any ideas on how intermittent short can be at fusebox, but not involve fuses or relays? Thanks.

 

How long is this vehicle sitting before the battery goes dead? I guess you are sure it's the battery because you are charging it or jumping it from another vehicle?

Does it do fine if you drive it everyday?

 

Hard to tell due to intermittency, it usually starts after being left for days indicating it hasn't shorted during last drive. But when short happens, it's usually been sitting a few days, so I toss the charger on.
Don't recall driving it one day then not starting the next, so I told the wife it's probably OK to take to work but she doesn't like my probably. Has never been a problem leaving for a few hours.
alternator gauge doesn't seem to indicate when it's shorting.
thanks

 

I was just making sure it wasn't sitting for months. Most modern cars cannot sit much over 2 months without risking the battery going dead.

I would say you have two probable causes.
1. A intermittent battery
2. A very slow drain on the battery.

To see if you have a drain on the battery, take the neg battery cable off and put a testlight on it like the diagram below. If the testlight glows bright, you have a drain on the battery somewhere.

 

It's 2, slow drain, trouble light lights with only single cable to fusebox (starter and relay disconnected.) Only way to unlight trouble light is disconnect that one fusebox cable.

With just the fusebox connected, trouble light's on, even with fuses and relays pulled.

It would be reasonable to tell me to get a circuit diagram to see what goes out of fusebox without going thru fuses. But manuals may not be that specific (just show fused wires.) I was hoping someone may have seen something similar, or know what short could be dependent on fusebox cable, regardless of fuse installation. Thanks,

 

Helm, Inc. can sell you brand new factory shop manuals when they have them in stock.

I just searched eBay and found two you might be interested in:

1992 explorer wiring diagram items - Get great deals on eBay Motors, Collectibles items on eBay.com!

 

For a experiment, disconnect the alternator. It's connected through a splice in the harness, and I am not sure where the splice is in relation to the wires you are taking off. It can go bad and cause a drain also, even though it charges when the engine is running.

 

Yeah, one of the diodes inside may no longer be doing its job.

Most auto parts stores can test alternators on the bench if you bring 'em in.

 

Still shorts with the alternator disconnected, and all fuses and relays out.

Last time this happened, a few months ago, I disconnected ground. When I reconnected ground, I thought I heard a click under the hood, and the short disappeared, till now.
Sounded like behind the relays (under the fuses.) So I thought it was a bad relay. But still shorts with relays out.

 

This diagram shows a underhood fuse box (I am assuming it's under the hood). Have you tried pulling fuses in that box?

AutoZone.com Repair Guide Image

You really do need a good diagram, and I don't have any for that year and model.

 

Here's another diagram with a little bit more in it.
http://www.autozone.com/autozone/rep...ngine%20wiring

 

Wife needed car so had it towed to nearby shop, bright trouble light indicated bad short. But they said no short, leaking only 1/4 amp.

I had ground off and know how to make short go away: touch ground to battery -, causes moderate spark but "unshorts" it. Touch ground again, no spark, as if shorting a capacitor.
We could pull - cable, touch it to battery post until no spark every time we park. But that's as much a pain as leaving cable disconnected every time it shorts. Since we don't know if it's shorted without testing, that means pulling cable every time we park.

Thanks for ideas, you can give this issue a rest but reply if any similar intermittent fusebox cable with pulled fuses short solved.

 

1/4 amp is too much drain for a normal system. Around .070 amp is considered the upper limit, you are at .250 amp.

 

Thanks for your update, I thought it high but they couldn't find it and I think it's been worse.
It started after being parked 2 days. I'll keep checking it.