I have narrowed it down to when I stop the car at a light and my electirc fan is on then the volts seem to jump all over the place from 12 to sometimes almost 16 volts. With the fan off the volts are stable between 12 and 14 volts. Could this be a bad ground or do still think it is the voltage regulator? Again it only does it when the fan is on. Thanks, Erik

What do you have for an alternator? It's possible that when the electric fan is on the electrical system in your car is drawing more than current than your alternator is capable of producing.

Paul D.

I just upgraded last fall to a 100 amp alternator. All I run is an MSD box, electirc fan when I need it and the radio. But when driving at night I obviously have my lights on too. I took the cover off the voltage regulator and it looks brand new. What about the horn relay, what kind of affect does this have on a charging system? Sometimes when the volts shoot up i can hear the fan speed up too.

Thanks, Erik

You can buy a solid state regulator to replace the old contact style. They're much more stable and they bolt right on and plug right in.