Jeep Just Died WTF

2000 Jeep Cherokee Classic 118k miles, stock, runs great, except....

Ok, so a couple weeks ago I posted an issue I was having with the "Check Guages" light coming on and my voltage guage was pegged to the max...

It's happened a couple times since, and I've had my mechanic friend test the charging system and everything seemed to check out O.K.

Today, I drive back from my night class no problems until I get home. About 10 mins or so after I shut it off, I get back in to go to Giant real quick, turn the key, and all I get is a couple lights on the dash that are really dim! I turned the key again, and there were no lights..... NOTHING worked.... no crank, no powerwindows, no locks, nothing!

I am pretty pissed cuz I need this thing available first thing tomorrow!

Does anybody know of any relay or fuse or anything that could have burned out/come loose????

Also tried searching, to no avail. Anyone, please...

Fuses, relay's, battery, cables and grounds. With a catastrophic failure, I'd check the basics first.

x2, Battery, cables, PDC--grab a multimeter and have it!

I had the exact same thing happen. Couple of instances of "check engine lights" etc... one time a few months previous a dead battrey. Then I was driving it, parked and turned it off. Tried to start it and nothing. No lights, minimal guages and if I turned the key everything died.

Turned out to be my alternator and battrey. Simultaneous failure. Good luck with the fix, hope it's something simple.

Well, my battery is about a year old (interstate)

I've been told that it might be a bad voltage regulator, which I think is inside the alternator, but not sure.

I just hope it's something straightforward like that instead of some weird bizarre electrical gremlins...I dont have the patience to put up with that crap

Alright, so maybe the battery is screwed....

I just put a booster pack on it and all the lights came back, even the underhood light.

tried to crank it however, and everything went back out. Charging booster now.

I'm guessing the alternator is the culprit here?? Charging the battery intermittantly??

Sounds like a bad connection somewhere. Check both ends of all the cables.

JJacobs said:

Sounds like a bad connection somewhere. Check both ends of all the cables.

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x2

NewToJeeps said:

Well, my battery is about a year old (interstate)

I've been told that it might be a bad voltage regulator, which I think is inside the alternator, but not sure.

I just hope it's something straightforward like that instead of some weird bizarre electrical gremlins...I dont have the patience to put up with that crap

Click to expand...

Voltage regulator is in the PCM.

wim

First of all, thanks to all who replied on such short notice.

This morning I put the booster pack on it and it cranked over real weak but started. Called up my mechanic and told him to expect me.

As I was driving, my "check gauges" light came back on, voltage gauge pegged to max again, and then soon afterwards, the "abs" light came on. All this time, all these lights are faintly flickering.

I got it to his shop, and he did a quick test on the battery and it failed. He said that the best thing to do was replace BOTH the battery and the alternator.

I guess this is the same thing that happened to willam a couple posts back.

Again, thanks for all the support guys.

It still can be the cables or connections. Sorry, but I certainly don't trust your mechanic who says to replace multiple parts at once. You'd have a better chance taking it into the autoparts store and having them test it. And I think william probably got screwed too. The battery and alternator don't got out at the same time.

Sorry for the pessimistic side. Good luck with it anyway.

winterbeater said:

It still can be the cables or connections. Sorry, but I certainly don't trust your mechanic who says to replace multiple parts at once. You'd have a better chance taking it into the autoparts store and having them test it. And I think william probably got screwed too. The battery and alternator don't got out at the same time.

Sorry for the pessimistic side. Good luck with it anyway.

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x2

If you had an old battery I would say that it wouldnt be bad to replace it anyway, but a bad alternator *shouldnt* kill a battery, nor will the reverse happen. Check the alternator. When I pulled mine off I found that the cast iron case of the alternator was actually blown apart, must have seized a shaft and threw everything out of wack and almost gredaded itself.. but my Jeep had also been sitting and the battery was junk (Ironically I actually did have both go at the same time.. but the battery tested bad and the alternator had physical damage done to it.. so alternator went bad, then the Jeep ran OK for a short while when I was moving it to storage, then while it sat in storage the battery killed itself).

I picked up a JY alternator and replaced the battery and life is good. I never had strange voltage spikes or situations like yours though so I cant vouch for the alternator being bad. Take it out, bring it to autozone, I thikn they have a tester there usually.

Edit: Thinking about it more, if your alternator IS bad and the voltage WAS really spiking all the way you could have fried any number of things unless there are safety backup regulators before the computer components, which I would expect there is esp where the Jeep is still running at all. If the voltage spiked to a rediculous level I suppose it COULD have damaged the battery. How long would it spike for when it did? Did the voltage stay up for a while or drop down eventually? Did you keep driving if the voltage spiked or did you turn it off and try to get it to drop to normal levels?

Sounds like an alternator...which over time can certainly kill a battery. I'd do both, but then again I do my own work and like to err on the side of over fixing things in my DD.

Depending on how old that battery is, I'd probably just replace it along with the alternator. It definitely sounds like your alternator is fried though (not sure where the regulator is, could be in the alt like some said, could be in the PCM like wim said, but the rectifiers are in the alternator - it's just a three-phase standard bridge rectifier consisting of six diodes) so I would replace that. It should be pretty easy to figure out with a DMM, or at worst, a student grade oscilloscope if you really want to know what's going on.