95 Tahoe- Voltage Dropping at Idle

[gradymotorco]

Hey everyone,

My 95 Chevy Tahoe (350 TBI, not the Vortec) has all of a sudden began dropping back to 12 volts (according to the voltmeter on the dash cluster) whenever the truck is idling. Once you give it some gas, it gets back to 13-14 v. Up until this week, it always read a steady 14 volts, even with the blower motor on high and highbeams on. Any idea what my problem could be? I was thinking that maybe the voltage regulator had gave up, but the electrical side of a vehicle is not my area of expertise.

Thanks!

 

[Rand]

possibly the alternator is worn out and not working properly. Ie it needs higher rpm to produce.

 

[abycat]

99.99% sure its the voltage regulator.

 

[gradymotorco]

I know on GM products the voltage regulator is located inside of the alternator casing, I wonder if I would be best off replacing just the regulator or going for a new/rebuilt alternator?

 

[abycat]

Id get a new or rebuilt one. The chances of the rest of the alt being pretty worn are fairly high.

 

[dave1251]

Originally Posted By: abycat
Id get a new or rebuilt one. The chances of the rest of the alt being pretty worn are fairly high.


This.

I had the same problem before in a 99 Yukon but the alternator was done before I could make it home. It gave you this much of a warning get a new one ASAP.

 

[tinmanSC]

This happened in a Grand Prix I owned years and years ago. Get a new alternator quickly! Chances are high it's about to blow. I did not heed the warning and it left me stranded 100 miles from home while doing a favor for a friend. We were both hosed.

 

[Chris142]

I'd get the battery tested first.

 

[JHZR2]

Originally Posted By: abycat
99.99% sure its the voltage regulator.


+1 Though my 91 BMW does this despite a new regulator...

 

[vssjim]

check voltage at battery and at the positive post on alternator to make sure it is alt and not a bad connection at battery etc. first.

 

[TFB1]

Originally Posted By: Chris142
I'd get the battery tested first.


This^^^

If the battery is failing, it can cause voltage to be lower at lower RPMs because all the current the alt is producing is being used just the keep the battery up... No alt produces as much current at low rpm as at higher speed but should produce enough to keep battery above 12v...

BTW if not the batt I doubt it's the regulator, they don't have effect on RPM, but more likely a failing winding or rectifier inside the alt...