reposting since I've looked into the problem some more and my last post was pushed way down.

When I turn my car on sometimes the alternator isn't charging. The SRS light will be on because my voltage is low and if I put a load on the alt. the battery supplies the power, the alt just sits there. I have to rev the engine up to 1700 Rpm's or higher before the alternator starts working and the voltage goes up. I can then put a load on the alternator and it will be creating the power, not the battery. The alternator light isn't on when this is happening, maybe it dosen't work since all the warning lights are messed up in my dash, except the SRS and seatbelt lights.

Do I need a new alternator? I have the 100 amp alt and there is a plastic casing on the back, and I've been told that the brushes and voltage regulator are internal and not replaceable. what do I do? new alt?

Thanks! you guys are a big help.
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My 91 245