Need Help with Charging System Problems for 97 Jeep Grand Cherokee

Long story short, I went off-roading today and after I ran through a mud pit (wasn't very deep, maybe up to the wheel hubs) and I think I killed my alternator and messed up my charging system on my 97 Jeep ZJ

4.0L. My volt gauge normally sits at 14 and after running a mud pit it was sitting at about 11 and about a mile down the trail it finaly went below 9. I barely made it home (60 mile drive) on just the battery's charge. I went to the local parts store and picked up an alternator and

swapped it out thinking that would solve the problem. Since my battery was dead after the drive I borrowed the battery from my girlfriends truck to start my truck up. Well it started up fine but the volt meter was only sitting at 11 on a brand new battery, and as soon as I disconnected the battery my truck would die. Finally I got my girl to sit in the truck and give it some throttle to keep it from dieing while

I swapped the batteries, which worked but as soon as I installed mine the volt meter dipped below 9 again and about 15 seconds later the truck died. I cleaned out the engine bay REALLY good in order to install the alternator and cleaned all the wiring on the alternator, battery, the grounds and even the electrical connection to the starter.

Am I missing anything here? Is there anything else that could have gotten messed up in the mud that would prevent the alternator from charging? Any other ideas?

Thank you, Fred R.

Reply to
fredr1980
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Does your alternator have an -internal- or -external- voltage regulator.

Reply to
Lawrence Glickman

If you have an external voltage regulator, replace it. If the voltage regulator is built into to alternator, look for a broken wire or bad connection someplace.

Lawrence Glickman wrote: >

Reply to
Mike Walsh

The fan belt likely just got polished up so it doesn't grab the alternator pulley. This happens all the time to my Jeep when I take them out to play in the mud. Mud = liquid sandpaper.

Now that you ran it open voltage with no battery, the computer is very likely fried as well as the new alternator likely puked out it's electronics.

Well, when my old roommate ran his with no battery thanks to an incompetent shop that forgot to tighten the cables so one fell off, he killed the new alternator, the computer, the ignition module and his stereo. Hopefully you are luckier....

My test for a polished up belt is to take a cold off engine and try to hand slip the alternator pulley. If I can hand slip it, it will not grab good enough under load to charge. The alternator takes a few HP to spin up under load.

Your system has the regulator in the computer which is an expensive fix and unlikely to have been caused by mud unless you got water into the computer's plug.....

Mike

86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >
Reply to
Mike Romain

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