This morning i started up my 2001 Cherokee and everything worked fine. I went to a friends house and left it for three hours. When i started it and the check gauges light came on. I looked at the volt gauge and it was buried at 9. Well i stopped and restarted it and it went to 13.8 and after a block it went to 9 again andthe check gauges light came on. I let the truck sit and it seemed to work ok. Well i went to autozone and Gomer behind the counter tested my battery and alternator and told me "your voltage regulator is bad time for a new alternator". I left abd removed the alternator and found the case was cracked really bad. Well i brought it to checkers and they tested the alternator is testing good. I went ahead and got a new one because maybe the voltage regulater is bad inside and might be going bad. So if it isnt the alternator what could it be?

 

Voltage regulator is in the PCM. Sounds like a connection/ground issue, if not PCM could be on it's way out.

 

Most likely the alternator. Install the new one you purchased.

 

check your alt fuse it should be fuse 8 in your pdc

 

I don't think the alternator is fused for an 01 through the power distribution center.

http://www.lunghd.com/Tech_Articles/...tification.htm

 

Is your belt tight?

 

Well i replaced the alternator and tightened the belt (im ordering a new one tomorrow) and it seems to run fine but the alternator gauge is running a small line under the 14 on the gauge. I remember before it ran at 14 exactly in the middle of the gauge.It makes me wonder so im gonna pull a battery i know is 100% and try that otherwise im driving it just the way it is. If tye voltage regulator goes out then i will know where to go next. Its really dumb that they put the voltage regulator in the computer so i have to pay for the piece of crap to get reflashed. I would love to meet the guy that invented that in a dark alley......i know i would make it out.

 

Yep, a failing PCM can cause this. The old one in mine did EXACTLY what you described yours (OP) doing. Fortunately, I had another PCM that was known good that I could swap with temporarily. When swapped the issue went away, so I ordered a rebuilt PCM on ebay for a couple hundred. No problems since.

 

Always best to verify your charging system. Takes 2 minutes with a simple multimeter. Buy one if you don't have one.....you can get one for as low as $10. A pretty darn nice one for $25. It is a critical tool for anyone working on their XJ.

Put the meter on DC volts range and put one lead on each of the battery cables with the engine running.

With a properly charged battery and a solid charging system, you should see about 13.5 to 14.0 volts on that meter.