Voltage guage @19v

As the title says my guage jumped to 19v along with the check guage light at interstate speed. Once I exited the freeway and was idling at a red light it went back to the normal 14v. It has repeated this several times today and is now sitting in the driveway. Don't really want to drive it till I know what's going on. Any ideas? Thanks Al

sounds like the regulator in the altenator is going bad.. pull the alt and have it tested.

You should be able to just check with a voltmeter. it might be a bad ground at the gauge as well. local autoparts places can usually check the charging system in the car. give those a shot before removing everything.

Sean

The alternators in the newer jeeps don't have an internal regulator, it's in the PCM power control module.

Year?

I have heard of this on some newer models where the PCM generates the Field voltage.
Check for good battery ground to the block and body.

Sorry for lack of info. My XJ is a 1997 4.0l. It will be a day or two before I'll be able to check it out. Just wanting to get some ideas of where to start. I refuse to throw parts at anything. Thanks, Al

Anytime you get a suspect reading from the IP voltmeter, replicate the "problem" and verify the reading with a DMM.

Period.

The IP voltmeter is a notorious liar in most cases. It will typically read low (anywhere from a bit to several volts!) but you should always verify suspect readings before you even think about throwing parts at a problem that it indicates.

my 2000XJ recently had a similar problem. voltmeter would peg at 19v. jeep would run ok and after a while it would go back to its normal 14v. a week later it wouldn't start for my daughter and she had to jump it. then another week it wouldn't start for me at work. it would start with a jump but wouldn't idle. i started with the cheapest fixes first, and took off the battery cables, cleaned them real well with a wire brush terminal cleaner. put them back on, the battery turned out to not actually be dead, it started right up and hasn't acted up since.
so i think it was just bad connections on the battery cables.

Which is why I suggested he check his ground connections/wires to the battery. No parts, just inspect and clean as required.

The problem with the OBDII voltmeter setups is the voltmeter is not a direct read instrument. The voltmeter is a guage like any other in the instrument cluster, and is run by a data stream from the PCM. An abnormal reading on the Voltmeter only tells you that you have a problem. To make sure you understand you have a problem, the folks at Jeep seem to have programed the PCM to read either very high in the case of a charging problem not related to the Alternator, or to drop to zero when the Alternator is not charging.

Thanks for all the replies. I've only owned this XJ for about a month and I'm still addressing some issues. I'd planned to pay some attention to the battery cables at the battery since someone has used the clamp-on type ends. I may just replace the cables. I myself have used the clamp-on type ends but find that it's just another place you may have a connection/corrosion problem. I'll have some time this afternoon after work and those afore mentioned connections will get my attention frist.

Skyblue, Sounds so similar to the problem you had.

Zuki-Ron, the makes sence how they designed it to read high to get your attention. That's something i'd never knew unless a place such as this exist with folks that care to share knowledge.

5-90, That's good advice. I've heard that factory in dash guages are little more than "idiot lights with hands"

Too All... Again, thanks, Al

i have same problem in a 98xj.. any updates?

re read through the thread...entirely it might make more sense.

Thought I'd posted my findings But noticed I didn't. It was a corroison on the positive battery connection. Sorry for the late post....Al