XJ charging issues

[Loco]

So here's the problem:

2 nights ago I started the jeep and the volt meter read 12 volt and the lights seemed dim. As I started out the voltage dropped to min and the check gauges light came on. I stopped at the side of the road and put it in park and restarted and the volts read a full 14. This situation played itself out the same way several times during the day yesterday with the issue being resolved by simply restarting. Later in the day, however, On the way home the stop and restart...

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[Baja]

Sounds like ecm to me. On XJ's the voltage regulator is built into the computer. It is a fairly common problem. You can test it by using a test light on the field wire comming from the computer to the alt. No power, no charge. I also have a computer from a 98 that you can try to see if that fixes it. I can bring it to the meeting Thurs.

 

[bradleyfitz]

I would test the battery. Any time I have had spiking voltage it's from a battery that is on it's way out.

 

[chunkytrunks]

I would test for power to the altenator like Scott said. Basically you should have somthing like 4-8v at the connector on the altenator(power going into the altenator). If thats good then Like Brad said test the battery and check all your grounds and wires.

 

[Loco]

Battery was drained a bit from limping it home this morning but I put on the charger for a bit, reinstalled the alt and cleaned up the terminals. Went to go and start it, opened the door, the light came on (was more off than on before, not on at all at the end) and it fired up and volt meter went right up to 14v. Did a couple of off-on's, 14v every time. Just drove it about 20 kms, no prob. So hopefully that was it.
I will be carrying a spare batt with me for the next couple of days just in case (finally charged up the yellow top i won at SF 09).
Thank you Baja for the offer of the loan of the ecu, I will decline for now but will contact you if anything else arises.
Thanks also to John, Brad and Matt for the quick responses.
Hopefully this is the end of this thread. Finger's crossed.

 

[Loco]

Well, that only lasted 2 days. Starting yesterday the problem is back. Tried cleaning the terminals even more, nothing. Tried a brand new yellow top, not that either. Sooo...it's looking more and more like the comp is is the culprit.
Baja, if your offer is still open, I would like to borrow your comp to rule it in/out. I will PM you.
Any other suggestions/ideas are welcome.

*as a note of interest, the driver's door light issue came back at the same time as the charging issue. Coincidence? Please discuss...