Hal StClair

iTrader: (3)

I'm having issues with a 2004 GTO alternator over charging in my 1965 Olds VC swap. I've run the white wire to battery + and have run the white to the idiot light on the car. The idiot light doesn't come on at any time unless I ground it and the alternator is putting out 17.2 volts. Isn't the terminal on the alternator where the white wire goes supposed to read as a ground when stopped. Anyone had this problem? I'm guessing a bad regulator? Any help will be appreciated. Thanks,Hal

downset71

Do a search of all my posts. I have answered many times

Hal StClair

iTrader: (3)

Thanks and I have gone through all your posts on the subject but they don't answer my issue.
I have it wired as it should be but still have the problem. Does the brown wire terminal at the alternator show a ground signal when stopped? Mine doesn't thus it won't turn the idiot light on. I can't seem to find an answer and believe me, I've spent hours looking. Anyone?
Thanks again, Hal

1981TA

iTrader: (7)

Does this help:

Hal StClair

iTrader: (3)

Thanks for the picture but I have it and still have 17+ volts running. The car has the idiot light and a resistor in parallel, factory installed ( I guess a redundancy if the light burns out). If I ground the wire the light works but doesn't light up when hooked to the alternator. When I check the terminal at the alternator with an ohm meter I get nothing, the reason the light doesn't light up. I'm guessing it's the regulator but don't like to just change parts without knowing.
Still puzzled........

1981TA

iTrader: (7)

It should light up when grounded, provided the other lead goes to a hot of some sort. This proves your light circuit is good. Have you tested the resistor with an ohm meter? It could be the wrong value (i.e. 200 ohms) or just bad. Another thought: disconnect the weather pack connector, and make a jumper with a 470 ohm resistor in it and run it to hot.

Or, take the alternator to Autozone, Pep Boys, O'Reilly's, Advance Auto, etc and have them test it.

LS_Junky

I bet the regulator in the alternator might be bad..

downset71

Not matter how u wire the trigger wire ( either right or wrong ) u should never get more than 14.5 V output. Sorry i didnt read your orig post better. Haha. Does sound like the internal regulator is fried

Hal StClair

iTrader: (3)

I tried running a 470 ohm resister straight off the alternator and it made no difference. I pulled it and brought it to 3 different parts stores and no one could check it-it kept blowing the breaker. Anyway, I picked up a new one and had it tested before bringing it home tonight. The darn idiot light still doesn't light! I couldn't run it yet as I have a PS line removed but hope to tomorrow. I did check the alt pin and there is some resistance so it's back to the drawing board on the dash light.This is getting crazy!!!!

downset71

If u ground the factory idiot lite ( in your harness under hood) wire someplace under the hood does it light up? ( totally disconnected from any alt. wires). Just to confirm the lite works with the key on

Hal StClair

iTrader: (3)

I grounded it and the light comes on. I'm going to try a separate light straight from the alternator to 12 volts and see what happens.

downset71

Maybe the bulb+additional resister is too much ohms. Dont make sense

1981TA

iTrader: (7)

You will cook the alternator if you do that.

Hal StClair

iTrader: (3)

Running a light from 12 volts straight to the brown terminal lights up so the alternator is doing as its supposed to( ground signal). The resistor and idiot light are supposed to be parallel wired so the resistance should be the same as the light. I'm wondering if the PO may have played with the dash wiring and changed something. I may have to pull the dash to see. Ain't this fun....

downset71

Try the separate light. Honestly mine is still hanging under the dash. I did the Covan classic dash with all new gauges and never put the new ALT light where its supposed to be. Just a simple 194 bulb and socket setup

1981TA

iTrader: (7)

If you wire the resistor and a light in parallel, you effectively halve the resistance (235 Ohms, instead of 470), which would result in a higher than desired charging voltage from your alternator. It would also result in the light not turning on, because half of the current is flowing through it - i.e. not enough juice to make the filament glow.

Moral of the story: Use one or the other, but not both.

Hal StClair

iTrader: (3)

You may have something there in the parallel circuit. I don't know the size of the factory resistor but the factory 194 bulb is only 52 ohms. I'll try to jumper out the resistor and see if that works. Thanks for all of your imput's, this thing has me miffed and a new set of eye's on a problem is a lot of help. Hal

Hal StClair

iTrader: (3)

Finally figured it out. The factory has a resistor wire running from the ignition switch and it runs parallel with the light. I removed the resistor wire from the circuit and all is fine. Light works properly and it's charging @ 14.5 volts. Happy days are here again. Now on to some of the other issues....

downset71

Very good!