03 Liberty overcharges and other electrical woes

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New Member
Dec 24, 2023
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Hello all,
New guy here, I’ve been scouring the forums hoping to find some answers to some problems I’m experiencing, but haven’t had any luck, and this looked like the best place to ask.

Background information
03 liberty V6 with automatic 155k miles, prior to the current one, it’s not really had any issues other than a fuel pump. Took it hunting a couple weeks ago up some pretty gnarly washouts and the engine got completely soaked. Having jeeps before, this has never been an issue before, but the liberty did not like it. Everything continued to run like normal for a couple miles after the puddle and then the gauges went out. I assumed something was just wet or a connection bumped loose so we just kept driving for awhile until til the gauges started flickering back on and off, and I could see the temperature gauge was starting to get a little past half way. I pulled over and got under the hood a found a mess. The engine was hot, cooling fan was not working, and the battery was so hot that you couldn’t put your hand on it and there was steam coming out of it. I realized the battery was fried, and it must be overcharging like crazy. Left it that night to cool down, and brought it home the next day.

Current issues
The alternator was putting out 19+ volts. I had hoped it was just a bad alternator but I replaced it and the cooked battery and it was still charging at 19. Brought the new alternator back to the store to have them check it and it tested good three out of three times. They also checked my original alternator and confirmed it was bad. I have tested the battery temp sensor, check the alternator wires to the PCM for shorts to earth, removed and cleaned all the grounds I can find, and I cannot figure out the problem. I believe the internal regulator has failed in the PCM or something is making the PCM think the battery is low and it’s sending the alternator wide open to try and charge.
Along with the alternator, the cooling fan, and A/C both stopped working and now it won’t idle. If I start it a hit the throttle and hold it around 1100 it will stay running but as soon as you let of the throttle it dies.

Any help is greatly appreciated