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Old 05-13-2013, 07:19 PM   #1
Join Date: May 2013
Posts: 2
97 Wrangler Charging Issues

Hello -
New to the forum but been reading up on this issue in depth. While driving home from work about 2 wks ago my TJ (97 4.0, manual) Check Gauges light came on. When I got home I checked the battery with a Multimeter and was getting 12.3v, so no charge when running... Thinking the problem was in the alternator (like most cars) I replaced that, but to no avail I still had the charging issue... After a bit of reading up on the issue I gained the knowledge that the Voltage Regulators in my Jeep are located in the PCM(ECM) not on the alternator as usually they are. So I checked all connections as I read that Jeeps are particular about connections; I ordered a replacement PCM; got the PCM and plugged it in, the jeep ran great.... for about 45min.
It was charging perfect so I took it out for a spin and like I said 45min later Check Gauges light again. Pulled the PCM out and it was hot to the touch (too hot) So I figure its fried...
Again with some reading and after already spending the $190 on the (now fried) PCM I decided to go with doing the External Voltage Regulator. Got that together and all wired up only cost $25. So start the Jeep up and now I'm getting 14.8 - 15.5 volts; overcharging...
I hear that the Autozone voltage regulators are shoddy so I get another one from a Junk yard for $8; plug it in and the same thing 14.8 - 15.5 charging volts...
I begin to think back and when I originally got the replacement alternator I selected to get the 90amp and not the 75amp alternator from the parts store as I'm running a couple of Fog lamps and figured it wouldnt hurt to have a few extra amps.

So my dilemma... Whats causing this thing to overcharge? Could it possibly be the higher amp alternator? Doesnt make sense to me if the voltage regulators are doing their job they should regulate the amount of amps coming off of the alternator...
I'm at a bit of a loss any help is appreciated. Sorry for the lengthy write up just trying to give all the background. Thanks!

If it matters I'm running a Optima Red top battery.

Dhook97TJ is offline   Quote Quick Reply
Old 05-13-2013, 07:26 PM   #2
Join Date: Dec 2012
Posts: 2,631
Welcome to the forum, I'm sure someone with higher knowledge might be able to give you some proper advice regarding this matter... wish I could be of help but if you took advice from me, I'd end up owing you money for repairs
RevCo666 is offline   Quote Quick Reply

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