The alt. isn't charging. Had it checked and it is fine. I have read about a resistor needed. I have ultralight gauges and am using the red light from ffr. Do I need a resistor in order for the alt. to charge? The light never comes on.
If the light never comes on, you don't have the exciter circuit functioning.
The light is in between the battery and the alternator. When you first turn the key on, it shows that battery voltage is being applied to the alt. That's why it lights up. When you start the car and the alt starts putting out a voltage, the potential (read voltage) on both sides of the light is equal and the light goes out.
First thing to do? Test the light. The downside of not using the resistor around the light is, you can't tell when the light burns out AND, when the light burns out, the circuit is open (without the bypass resistor) and that means, no exciter voltage is applied to the alt and it won't start charging.
Whew! Got that? Bottom line for now, check the light with something, (battery charger?) and make sure it's OK.
Ok so I found the green/red wire under the dash not attached to anything. I had a wire diet done by Roger Stein and its a stock build. So should I just hook that wire up to the light and put a resistor in? Do I need a 12v wire hooked up with the "exciter wire" on the light?
OK, one end of the R/LG wire has to come from somewhere. It should come off your IG switch. From there, it should go to (thru) your ALT light (with the bypass resistor in parallel) and from there to your alternator's C154 connector.
That will supply the exciter voltage to your Alternator.
Which wire wire do you have the end of? The one that's attached to the alternator or the one to the IG Switch?
I have a red with green stripe attached to the light and I found a green with red stripe and I traced that to the alternator. Do I need to ground the light or does the alternator act as a ground? Right now the light is hooked up with the red with green stripe wire and a ground.
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