Voltage Regulator resistor missing?
 

I just had to replace my alternator about 2 weeks ago because it failed. I tried to just replace the VR, but that didn't help. So when I put the new one on everything was fine, initial idle voltage was 14.4. a few week later I noticed that it was at 13.1 and with ac and fan and radio it was at 12.8. Today I decided to do several tests to check for bad diodes and loose connections etc. I found nothing so I thought, I'd check the VR. The brushes are fine, but what I found was a remanufactured Bosch VR (typical as the alternator came from autozone), but there was no resistor. Not sure if there is one incorporated into the VR, but I thought it was strange. Anyways, I took that one out and put another one that had the resistor in and I am back at 14.4v. I'm guessing I can solder another resistor in because I do not want to take the entire alt back off just to return it for a replacement (esp since the guys at autozone all say the same thing "The VR is incorporated into the alt and it can't be removed.") So does anyone know how or what the resistance of this resistor is?

The resistor was added as a precaution in later VR's, it's not necessary to the function of the unit. It only comes into play if the VR goes completely open circuit. In that event, there would be no charging and no idiot light, because the light would have no path to ground. The resistor provides a parallel ground so that the light will come on in that rare circumstance. Don't waste your time, the old VR was bad and won't be made better by adding a resistor.

Thanks

This explains why my older 300D went flat without any idiot light. Replaced with a new voltage regulator and the problem was resolved.

Glad to know the light didn't turn on!