My alternator started going intermittent on my drive home from work. Alternator would stop charging (volt meter went down, lights dimmed, etc.) for maybe 30 secs to a min or so, then I'd hear the belt squeal indicating that the alternator was starting to charge again and start loading (causing the belt to squeal - I know, the tensioner might be getting weak or the belt is getting old and glazed too) and the belt would eventually grab and I'd get a working alternator again. This cycle would repeat and I made it home. No, my problem isn't just a loose belt - the belt is tight and turning the alternator, but on occasion the alternator will just completely stop charging and go into a no load state.
First question - apparently I could have either a Bosch 90 amp, or a Denso 75 or 90 or 120 amp? 4 options for the same model year and engine? Is that right? And none interchange, I have to get exactly the right one?
Second question - the field has to be excited for the alternator to charge, so I'm wondering if this is really an alternator problem, or do I have a wire to the field that's intermittent and causing the field excitation to come and go? I have parts of the service manual, and the field is connected to +12v on one side (through the ignition switch) and to the Engine computer (through something labeled K20 - perhaps that's circuit K20?) on the other. What's the engine computer's role in this and how do I check out that it's doing it's job?
I'd like to verify that I don't have any problems with exciting the field before I throw and alternator in there. I did a search and although there are lots of posts about alternators, I didn't find anything that really answered my questions or applied to the 1992 model year. Any help or advise would be appreciated!
Thanks - Tom