Hey everyone new to this forum, I've got a 00 Cherokee and the voltage meter spikes to 19 while driving down the road, usually at high way speeds but not always. It was doing it a couple months back but went way and now its back. I've cleaned every single ground on the jeep, put a new alternator and battery in and the problem is still there. I've tested everything I could think of with my multimeter and everything checked out good at idle. It does not stay at 19 long enough at idle to check it. the battery reads 13 at idle the stater reads about the same as well as the alternator. If anyone has an suggestions it would be appreciated. Thank you!

 

Sounds like the voltage regulator is going out, it's integrated into the alternator.

 

Which is inside the PCM correct? So I would most likely have to buy a new PCM if that is the problem..

 

What? No it's in the alternator. New vehicle have them built directly into the alternator.

 

Every forum I've read says that the regulator is inside the PCM in 91+ cherokee's

 

Oh... Well, I found this write up

http://www.jeepforum.com/forum/f11/e...-asap-1167297/

 

Thanks for that I appreciate it. May have to try that next doesn't look to hard to wire up. This is the most aggravating problem since I've owned the jeep haha

 

You could have bad cells in your battery too. I replaced the battery on my 2000 and it fixed it, I then went ahead and swapped out alternators too for good measure, nary a problem since.

 

Already put a new alternator in and battery a week ago and it didn't help the problem. I wish it was that simple for me haha

 

Bump anyone else. Thanks

 

The PCM is looking to keep the system voltage around 13 volts. It will tell the voltage regulator to add more charge if it gets a lower than 13 volt reading. Why is it getting a lower reading is the problem. Bad battery,bad or dirty connections, bad cables corroded or loose ground connections. Any of these will keep the PCM from seeing the voltage range it would like to maintain. Find the offending item or items and the over charging will stop. Some have said the problem comes and goes so loose connections may be their problem. Often a good cleaning of all the battery cable connections, at the starter,body grounds and at the battery itself will remedy the problem.

Ron

 

I've cleaned everything recently, I guess it wouldn't hurt to go back through and clean them again. Might just go ahead and buy some new cables even though there is no corrosion on them that I can see. Thanks for the reply

 

Update: Seems if I run my vents it brings the voltage down just enough that it will not spike to 19. Is there a reason why this would cause it not to spike? thanks

 

On one of these threads someone mentioned keeping an eye on the PH of the coolant. Just picked up some test strips from the local Cummins parts and repair place, less than $2 each.

 

My 1998 Jeep Cherokee xj the voltage regulator sit on. the outside of my alternator and is spliced into the main wire harness and I was having the same problems until I bought a new $320 optima battery but runs fine but also reads 13 amps before the battery swap it was jumping to 19 amps around town driving for short periods on and off