Alternator Overcharging 1998 Gen 2.5

[Salonika]

Noticed low voltage on the gauge last night. This has happened before, just a month or two ago. I thought I solved the problem by cleaning up some terminals. I had dimming lights at idle, slow wipers, fan, etc. Everything improved after a little cleaning, even though nothing looked very bad. Last night though the gauge went lower than it ever has before. So I broke out the multimeter and hooked up wires directly from the battery, and verified the gauge reading. It was down near 11 volts. Crap. Decided I might need to take another look at what I did before, maybe I missed something. To my surprise this morning when I started truck both gauges went up to 18.6 volts. Then my ABS light came on. I shut the truck off immediately and started doing homework. I believe my voltage regulator crapped out. I'm afraid to run any engine-on tests so I'm pulling alternator tonight for testing. I already ordered a new Mitsu piece because I'm sure that's my problem.

Did I fry my ABS controller?

 

[Eric M]

The 18v was more of a danger to your battery than anything else, as long as you didn't let it sit at 18v for too long.

 

[dieseltechJay]

It may be the voltage regulator is shot, or issues with your cleaning job. Again, if you're going by the stock dash gauge take it with a grain of salt. The gauge can be what's faulty. Always always always check voltage with a real Digital Multi-Meter.

 

[Salonika]

New alternator on. ABS light went off right away. Power back to normal. Now my alternator drive belt tensioner is rattling. Can't win.

 

[mr_ed]

Good to hear. Those symptoms (dimming lights, slow wipers/fan, at idle) are what my 98's doing right now.

Did yours have oil from leaking cam seals? My wife's 97 had the leaky seals which killed an alternator a couple years ago (all fixed now), but my 98 has zero oil leaks...alternator is clean as a whistle. Just curious if yours died from oil bathing, or if it was just it's time to go...

Ed

 

[jeep-N-montero]

I replaced mine a week or so back with a USA rebuilt Delco unit and couldn't be happier, now reads 14 volts and the lights don't dim if I run the blower fan on high like it used to. The famous valve cover leak was the culprit along with the power steering pump had an occasional drip that helped it along.

 

[Salonika]

Good to hear. Those symptoms (dimming lights, slow wipers/fan, at idle) are what my 98's doing right now.

Did yours have oil from leaking cam seals? My wife's 97 had the leaky seals which killed an alternator a couple years ago (all fixed now), but my 98 has zero oil leaks...alternator is clean as a whistle. Just curious if yours died from oil bathing, or if it was just it's time to go...

Ed

The factory one did, but it was replaced with an aftermarket. Then the engine was rebuilt and I went through 2 more aftermarket ones that failed for who knows why. Finally got sick of it and bought one from Mitsubishi. I actually still have slight dimming and voltage drop at idle but nothing like before. Not enough to make it into a project anyway.
With a good alternator, and several accessories on, I think some voltage drop is normal right?

 

[jeep-N-montero]

The factory one did, but it was replaced with an aftermarket. Then the engine was rebuilt and I went through 2 more aftermarket ones that failed for who knows why. Finally got sick of it and bought one from Mitsubishi. I actually still have slight dimming and voltage drop at idle but nothing like before. Not enough to make it into a project anyway.
With a good alternator, and several accessories on, I think some voltage drop is normal right?

Yes, some initial drop when you turn on lights or other accessories is normal, then the regulator tells the alternator to kick in to compensate. This is noticed more in winter than other times of the year.