I have been having a number of charging issues with my 66 c10 over the past couple of weeks. Rather than go in all the detail, let me tell you where I am as of right now.
I have an alternator with an external voltage regulator. I replaced the alternator about two weeks ago, and the voltage regulator last week. Since then, I have noticed a whining (buzzing) noise in conjunction with my generator light coming on. I first thought that the noise was coming from my alternator. This was not constant, just a few seconds per occurrence. When it did occur, the battery meter in the truck would go up and down - all over the place.
As it turns out, the whining noise was coming from the voltage regulator. I have no idea what the cause is.
I have tested all connections and grounds. All checked out. I even added a ground from the negative battery terminal to the body of the voltage regulator. Still no change. I bypassed the voltage regulator and confirmed that the alternator is pushing 17 volts, and the battery reads 17 volts when unregulated.
I replaced the voltage regulator again. The one that I took off had signs of heat on the back side. Put the new one on. Start up the truck and the volt meter shows 14 volts at the battery. No generator light; no noise. Turn it off, and then back on. Generator light comes on for a few seconds. At the same time, the regulator whines, and the volt meter drops to 12.5. Then, on its own, the generator light goes off, whining stops, and volt meter goes back up to 14.
I continue to be at a loss, and do not know if I should be concerned, or just leave it alone as the battery is charging.
