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??? electrical gremlins, please help

BSH

NAXJA Forum User
Location
Sauk County, WI
96 XJ, 4.0, Auto, power everything, plus aftermarket stereo & alarm stuff by a previous owner.

So, I had the bad headlight switch problem, blowing the fuse and cutting out my running & dash lights. I finally got around to replacing the headlight switch, taking apart the dash and remove the gauge cluster to do so. I thought, there must be a short somewhere to make this problem show up, so I found this loose end from the alarm system. I never used the alarm, not sure the guy I bought it from did, either. I removed a fuse on that lead (I traced it, it really is from the old alarm), and it was full of corrosion, as was the socket, and left the ends taped and securely not touching anything. I put everything back together, and my lights all work the way they're supposed to.

One thing odd, I have no fuse in the fuse block for the power windows (I think that's the position), just a wire coming straight out of the fuse block into the interior wiring harness. I had thought this wire was for the alarm, and left it unplugged (since I don't use the alarm), but then my windows didn't work until I plugged it back in.

But then, when I dropped it off for inspection, the shop said they found it with a dead battery. And when I took it home, a funny thing happened. I turned the heater on, from the off position. When I did that, all the gauges went down to zero and right back up again. The generator light came on. I tried it a couple more times, and got the same result. The heat works, the fan blows. When I got home, the gen light was off. Before I shut it off, I had my wife turn the heater on, while I listened under the hood. There is a strong single clicking sound from the main power distribution panel when the heater (or vent position, basically anything outside of "off") is turned on.

Any ideas? I suppose I'll find a dead battery tomorrow. If anybody has some good electrical knowledge about these beasts and can give me pointers, I'd appreciate it. To start with, I'd like a picture of a fuse block that's factory original. Mine's been modified for this alarm and who knows what else.

Thanks!
 
Bad blower motor or HVAC switch, common--POS wiring in those circuits.
 
Hmm, you think it's just a coincidence that this happened right after I was mucking around the dash with the headlight switch? It should be pretty easy to replace the HVAC switch, since I just was in the dash, just plug-n-play, right?
 
It'd be plug-n-play if there wasn't already an issue with it - usually the connector that it plugs into gets all melty from the heat of the arcing contacts. Get a new switch (BRAND NEW if you can, though it's a matter of time, problem is solved best by doing a relay mod to it, google for a page that explains it) and a new connector (one of the switches is just quarter inch quick disconnects, the other is some wonky plug) and splice it in.
 
follow-up question:
If it's indeed the blower switch, would that cause my battery to run down? I have a fairly new battery (about a year), and it's running down with the jeep just sitting there. Today I went out and it wouldn't start, showed 11.5 volts on my meter. When I drove it home, the volt meter on the dashboard was showing 14, so it appears to be charging when running.
 
No way to tell long distance.

Engine off, remove the negative battery cable. Hook up a 12v test light between the cable end and the battery terminal.

If the light has a SMALL glow, then there is a normal low current draw. If the light comes on BRIGHT, you have a substantial draw that is draining your battery and needs to be located and repaired.
 
It should probably be on the 20 amp unfused setting (if available) - with the probes in the proper holes for that configuration. Anything over a few dozen milliamps I would say is probably an issue.
 
Okay, how do I go about isolating what circuit is making the draw?

You can unplug accessories or try pulling one fuse at a time to isolate the circuits.
 
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