QuestionHi Roland. You have helped me before, and I need your expertise again. My alternator is giving me problems. I get static on AM radio, and it increases in pitch when the engine RPMs go up. Sometimes the battery light on the dashboard comes on. I checked battery voltage when the battery light was on, and it jumped up and down, from around 14 to over 20 volts.
Do you think replacing the brushes will resolve the problem? I'd like to get a brush kit and replace them. Can this be done with the alternator in the car, or does it have to be removed? If it can be done "in place", do you know the procedure? Thank you.
AnswerHi Bill
I would wonder about whether the field coil wires inside the alternator or the dark green wire from the pin 8 of the pcm to the alternator might be shorting to ground if you are getting 20v at times. The control of the voltage is performed by oscillating to ground one end of the field coil which causes a high voltage output. So check for the dark green wire to be shorting or not. Then I would suspect the alternator field wires inside rather than the brushes, which would produce intermittent no voltage rather than intermittent 20v. That would, if true, mean a rebuilt alternator rather than brush replacement.
I don't have any instruction text on brush replacement, in any case.
Roland
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