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Discussion Starter #1
Ok. I've got an electrical issue here that is pretty specific. - I'll start at the beginning:

I was born on December 29th , 19... Well, maybe I'll skip ahead a bit.. :D

Last year I bought an '89 XJ with the 4.0 I-6. I've been tinkering with it (new axles, tires, bumpers... etc... but nothing touching the electrical, yet) and had no electrical problems what-so-ever; until... A few weeks ago I noticed that the fuel gague was reading high one day. I noted it mentally, but since it's not my DD, I figured I'd get to it later. Then the next weekend that I took the jeep out, I noticed that the gage was pegged all the way past full. (clearly malfunctioning to the point of being useless), but again, I just ignored it.

Then the next weekend I was headding to a trail ride the night before an early run and when I turned my lights on, the engine almost died. - I ended up just going with my brother in his jeep, but that's not really part of this story -

So since the alternator was 17 years old, had 250,000 miles, and squeaked weirdly, I replaced the alternator. Then I started the jeep (after charging the battery) and I put a meter on it to find 11.9 volts while it was running. I brought the alternator back and had it tested and found it was good. So I reinstalled it and started looking at other things.

I replaced the main line from the battery to the starter (it absolutely needed it, but didn't help this problem) and I replaced the fusable link between the alternator and the distrubution block... - nada.

So I traced the lines that ran from the plug in the alternator and found that one of the two disappeared hopelessly into a wireing harnes, and the other went into a 6-wire weather-pac connector next to the battery, THEN dissappeared hoplessly into a wireing harnes.

I - just for a laugh - started the engine, and unplugged the connector. I heard the engine instantly go under a load (the idle responded accordingly) so I put a voltmeter on it and got 15 volts :)

So here's where the gas gage comes into play... Well, after I brushed out the contacts to the best of my ability I reconnected the weather-pac and was still getting 14.7 volts. (aprox- analog dial). AND the gas gage was working. I drove around the block with my lights on and checked when I got back and was still charging. SO I figured I just had a corroded connector, and I was done.

The next weekend, the gas was reading wrong. and sure enough, when I checked, I was not charging the battery. SO I pulled the connector and checked while the connector was unplugged to find that the gas was still pegged, and that the engine was indeed charging again. I reconnected and once again the gas was working and the the system was charging.

So my question is: Do I just need to replace that connector (which looks good, and I haven't heard of them going bad very often), Or do you think I have a short that is some where ( I personally am affraid that it's likely, considering the age) and is just giving me the ol' head-fake with the connector?

Or is there another explaination that I'm missing?



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I'd suggest getting a wiring diagram for the '89 and wringing out the wires associated with the alternator and that specific plug. With miles & age on the '89, a good service manual will come in handy.
I've used the reference area of my local library to find fairly good wiring diagrams. I think I used Mitchel manuals there.
 

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The plug pins might look great but the wire 3 or 4 inches back might be done. Next time it happens try just moving the wires associated with the plugs around and see if that has an effect. How many small wires are going into the plug on the regulator in the back of the alternator?
 

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Discussion Starter #4
The middle two pins of a 4 pin connector are used to connect to the alternator.
 

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Discussion Starter #5
I'd suggest getting a wiring diagram for the '89 and wringing out the wires associated with the alternator and that specific plug. With miles & age on the '89, a good service manual will come in handy.
I've used the reference area of my local library to find fairly good wiring diagrams. I think I used Mitchel manuals there.
Good advice.

I've got the Haynes manual, but I'll check out what the Mitchel has.
 
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