Ok, as part of my anti-theft protection, got one of those battery disconnect deals where you unscrew it and go which disconnects the hot side of your battery. It has a pigtail that jumps around the main cable to handle a small amount of juice for your clock, radio, dome light, etc. which came with 20Amp minifuse. The idea is cranking will pull too much juice through the wire and blow the fuse. The Wire (14? 16 Guage?) would be too flimsy to pull the current for the starter anyway.

So here's the mystery. I shutdown and all lights/accessories are off except the clock, the memory to the radio and dome lite ( I leave the door open). Pull the coil wire, unscrew the battery disconnect....bam there goes the fuse in the little pigtail. This only happens about 30% of the time, other times no problem. So I move up to 30 amp fuse...just to see....same deal.

Now I say...must have some sort of a short somewhere to get that kind of drain....Nope, if I do everything the same and just don't remove the disconnect, it'll sit there over a week and the battery is just as fresh as ever.

Any ideas what's causing the fuse to blow????

Aliens! :flipoff2:

Seriously, start pulling fuses from elsewhere to help narrow down the problem. Could be something you have in there that runs for a short amount of time before shutting off (big stereo stuff?), so it's enough to blow the fuse but not enough time to kill the battery. Also if you have a good ammeter you can start working through the system to figure out where the problem is.

Guess that's what I'll have to do (start running circuit elimination, but what a pain when it is an intermittent problem). The only things that I can think of is the ECU may suck a little power even after shut-off (I can't remember, is there an O2 sensor heater in the '88) or keeps some circuit or another open (but you'd think something powerful enough to drag enough current to bust a 30 amp fuse would be apparant, even if only momentary. Like I said only the dome light is sucking any significant amount of power so far as I can tell). The Alternator is getting weak, wonder if the built in regulator momentary malfunction might be a possibility?

Just had hoped one of the electrical geniuses on the board might have run across this at some time or the other.

Got nothing special in my junk from the stereo point of view other than the factory AM/FM/Cassette and a CB which I've checked has always been in the "off" position. No electric fans or anything. Almost seems like it could be something sucking juice when the engine is warm but not always.

Anyway, thanks for the suggestion. Anyone else got any ideas?

Only things I can think of that would pull 30 Amps or better are the starter and maybe the rear window motor...Fuel Pump???
Don't think the blower will pull that much, but it's always been off anyway.

Originally posted by dogsailer
but you'd think something powerful enough to drag enough current to bust a 30 amp fuse would be apparant, even if only momentary.
Could possibly just be a short somewhere too. If you have a decent voltmeter you can put it on the battery terminals and watch the reading as you wiggle wires, the volts will drop when/if it shorts. There's nothing stock that runs after you shut off the ignition so that's about the only thing I can think of since you don't have any other electronics pulling that kind of current.

Good luck, eletrical problems suck. :(

i think it is a short also, is this disconnect thing hitting ground somewhere when you disconnect it, like the hood of some other offending source of ground? I think it has to do with the disconnect because you would have a blown fuse or burnt wire elsewhere before the disconnect problem started up. Did this problem start up after instalation of the disconnect?