bad voltage regulator? (Page 1/1)
katie80 FEB 23, 08:16 PM
I have an 84 2.5L and I just tested the voltage of the alternator and it was a little above 15v at idle. this is too high correct? sometimes it drops to 14v on the gauge and the seeking idle issue I have stops happening. do I need a new alternator or voltage regulator? is it ok to be that high?
Forrest FEB 24, 07:33 AM

quote
Originally posted by katie80:

I have an 84 2.5L and I just tested the voltage of the alternator and it was a little above 15v at idle. this is too high correct? sometimes it drops to 14v on the gauge and the seeking idle issue I have stops happening. do I need a new alternator or voltage regulator? is it ok to be that high?



I just had the exact same issue. I think its due to a failing battery. I checked with a multimeter and it read 14.5v so my gauge was showing high. It eventually drops to 13-14v.
Again I think the root cause is a failing battery causing the alternator to work harder. You may try putting your battery on a charger. Once its fully charged fire up your car and see if it persists.
theogre FEB 24, 09:06 AM
Do Not Trust dash gauge. Put a volt meter on battery.
⚠️ If possible put meter to Alt output or red wire to side plug and alt case but often hard to reach and short the alt blowing the thing.

Maybe a low battery cause it or is a side effect of alt problems. Either case need to charge it if < 12v.
Crap battery cables won't help.

84 and early cars alt wiring is more complicated then most later years and often causes high volts.
See my Cave, Alternator Sense

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

katie80 FEB 25, 04:21 PM

quote
Originally posted by Forrest:


I just had the exact same issue. I think its due to a failing battery. I checked with a multimeter and it read 14.5v so my gauge was showing high. It eventually drops to 13-14v.
Again I think the root cause is a failing battery causing the alternator to work harder. You may try putting your battery on a charger. Once its fully charged fire up your car and see if it persists.



I tested with a multimeter and it was at 15v. I'm not sure if it has always been this high or not. the battery failing is not a bad theory I had a couple times where it got shorted by bad wiring and again a burnt out starter. I may get it tested somewhere.
katie80 FEB 25, 04:23 PM

quote
Originally posted by theogre:

Do Not Trust dash gauge. Put a volt meter on battery.
⚠️ If possible put meter to Alt output or red wire to side plug and alt case but often hard to reach and short the alt blowing the thing.

Maybe a low battery cause it or is a side effect of alt problems. Either case need to charge it if < 12v.
Crap battery cables won't help.

84 and early cars alt wiring is more complicated then most later years and often causes high volts.
See my Cave, Alternator Sense





I tested the voltage at the positive cable and a body ground and it was 15v. battery cables may be the issue. I planned on replacing them a while ago but never got around to it.
theogre FEB 25, 09:56 PM
15V is a bit higher then should be...
Should be 14 to 14.7v

Read alt sense in cave.
Jump alt out to pin A w/ Red wire on side plug.
If volt drops then you have wiring problems that need to fix ASAP. Running w/ the test jumper isn't good even if gets lower volts.

Replace an Iffy Battery and/or cables but may not solve this problem.
Use ACdelco battery cables w/ all side terminal batteries. Not knockoffs w/ lead battery terminals.

This problem(s) can be grounds, power wires, battery cables and more for 84 car. Even in C500 itself and that could melt or cause fires.