Dear Roy,
The truck had a no-charge condition, and I confirmed that the alternator was not working. I installed an aftermarket unit, and it put out 14.2 volts and 13 amps at idle. All was good, but I still had a charge light on.
I thought that I had a bad unit and changed it. Same problem.
I talked with some friends, and they told me that I needed to use a factory remanufactured unit or the light will not go off. When I got a factory remanufactured alternator, the counterman told me the same information but could not tell me why. He said that all aftermarket reman [units] will charge but will not turn the light off.
Can you help me understand why? Can you help me turn on a light in my head and off on the dash?
Dear Mr. Banovich
If there is a malfunction in charging system operation, the regulator will ground this circuit, which sends a signal over the CAN link to the PCM to illuminate the lamp.
I would venture to guess that your rebuilder is either using the wrong regulator, or it is one of suspect manufacture that is unable to communicate with the PCM.