Generator light coming on a higher speeds

[A1Avette79]

My Generator light comes on intermittently when I am driving at speeds over 60 mph. It glows brighter and stays on more steady the higher the rpms. At the same time my Voltmeter moves over to the right almost to the red zone. My alternator is new and my battery reading is fine.
Anybody have any ideas?

 

[73shark]

Check the voltage w/ a separate meter. Might be the regulator in the alternator. You didn't say but if the "new" alternator is a "rebuilt" one, then it could be bad. There just not that many good rebuilders.

 

[A1Avette79]

Thanks, I'll give that a try.

 

[GerryLP]

Check the voltage w/ a separate meter. Might be the regulator in the alternator. You didn't say but if the "new" alternator is a "rebuilt" one, then it could be bad. There just not that many good rebuilders.

I concur with 73Shark on the cause (but no editorial implied on the rest :L). The red light is tied to a diode rectifier which will make the red light glow if voltage is not being regulated within a certain range (i.e. it could be an under-voltage condition as well); however, the ammeter's reaction correlates the symptoms discussed.

Best bet is to take it to AutoZone and have them test it. Some of our more skillful members have actually been able to replace the internal regulator, but I have never tried it...hnoes

 

[G Winter]

I agree that it is most likely the regulator. If the voltmeter was not showing high volts I would say it was a problem with the brushes bouncing.
The regulator is not hard to replace,just have to read up on reassembly. You need to hold the brushes in place with a round toothpick or very thin wire inserted through the rear housing.

Glenn

 

[gmjunkie]

I agree that it is most likely the regulator. If the voltmeter was not showing high volts I would say it was a problem with the brushes bouncing.
The regulator is not hard to replace,just have to read up on reassembly. You need to hold the brushes in place with a round toothpick or very thin wire inserted through the rear housing.

Glenn

The Public Discount Auto parts store Fote Pierce Fl sells Blue Chip Alternator rebuild kits that come with new Brushes,Brush Holders,Brush Springs,Diode Trio,Regulator and Front Bearing for $14.95!! I pick up 4-5 kits for Chevy about every time I'm down there,I can't buy the regulator around here for that!!

 

[Mr. Chuck]

Alternator warning light comes on when the alternator output which is connect to one side of the lamp and the output from the trio-diode which is connect to the other side of the warning light are not equal. The trio-diode is also found inside the alternator, mtg'd on top of the regulator assy. Testing the alternator will tell you if the problem is in side, the replacement of either the regulator and/or trio-diode is not a big deal, especially with a shop manual, some repair experience and desire to avoid buying a alternator.