The Ruby just started doing this more recently.

At night, the dashboard lights flicker and pulsate, and so do the exterior lights to some extent. Battery voltage needle is unsteady too.

With the engine off, everything is steady.

The alternator is pretty new (probably 12k miles on it), do these things fail that quickly?

 

Your voltage regulator is oscillating. You can prove it by looking at the waveform with an oscilloscope. An AC voltmeter (can't respond to DC, might need to place a large 1 uF or so capacitor in series with one probe) will measure the AC component. Normally the alternator ripple will be very small, my guess without measuring is under 0.1 volts, 100 millivolts. If the alternator is under warranty, get it replaced, otherwise a new voltage regulator should fix it.

 

I didn't know the voltage regulator could be replaced separately... where could I pick one up? Last Detail doesn't seem to carry them, only the alternator itself.

 

Hey Thud,
You wont really find a regulator to buy seperately,its part of the alternator itself.Be sure the battery is good and holds a charge before replacing the alternator.Dont rely on the dash readings for that either.Always have a charger at home and fully charge the battery before replacing the alternator.

Alternators on C4s seem to go bad ,no matter which design.If youre in doubt what to check,have a good shop test the alternator and battery and see what they advise.
I had a semi new alternator self destruct under 5,000 miles.(the bearings gave out and broke everything inside)And that was the 7th or maybe 8th alternator I had replaced over time/warranty with an excellent battery.

One final test you can do at home(with the battery showing good charge) is to take off the serpentine belt and start the car for a few minutes...and watch the voltage for a few...if it remains steady for a bit but slowly drops a volt here and there,the battery is good.If it fluctuates constantly,look into the battery as being bad.With the belt off,the alternator is ruled out.Check the cables too for tightness and corrosion.

:)

 

My 93 turned into a "disco Vette" last year... :lol: ..it's the voltage regulater...it's all in one with the alternator...I replaced mine with a 140 amp heavy duty A/C Delco.... no problemo's since... :thumbs:

 

You can check the voltage across the battery with the car running, it should read approximately 13.7 volts. This will confirm a good alternator. You can also remove the positive battery cable then take notice of the idle. It should remain steady. As mentioned above, give the battery good charge.

If you are still unsure you can bring your car to an alternator shop and have them check it for you. They will certainly tell you the problem.

 

Howdy,
My 85 was flickering like yours but charged the battery ok, so I pulled the alt off (about a half hour) and took it up to Auto Zone and they put it on their bench test. The output amperage was sub par, diodes checked ok, and the volts were a little over 14. When put on a load their lights flickered the same as my dash. $115 later I was going home with a Duralast remanufactured one with a lifetime warranty. Installed it in 1/2 hour and no more flickering. I did notice that when it's charging, the alt whines alot. ExpoSaidThat :banghead: :banghead:

 

Voltage regulator :yesnod:

GM doesnt want you to know you can just replace that part instead of a $150 alternator.

 

So how would I go about replacing the VR?

Is that procedure in the shop manual? Can I pick one up at NAPA?

 

I've found that an inexpensive "alternator rebuild kit" will contain, among other things, a new voltage regulator. Will it work on your Corvette's alternator? I plead ignorance, but I'd be willing to risk the $15 or so to find out.

Larry
code5coupe
:seeya

 

Wow. Major auto parts stores, youtube, alternatorman,rock auto, etc,etc.

 

20 year old thread