Ok, I've got more data on my screaming alternator.When it screams, it's being loaded down-for sure. Gets hot, output voltage drops.Only occurs when engine is running-with key in run position without starting car,I measured less than 8A-normal.Can't measure the "failure mode" current, since it must be approaching 100A and my meter won't go that high. More likely when heated up,more accesories on. It's not the battery or the alternator (subbed them). Based on my looking at the schematics, it could be something in the ignition, since most of that is switched but not fused(!).The odd thing is the car runs fine at all times.I've tried moving cables around under the hood while watching the voltmeter across the battery. Nothing yet.
sredwine car has 195K

Have you tested circuits to find any large amp draws or shorts?
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See the 700/900 FAQ at the drop-down menu above right.

Thanks, Steve-use the FAQs all the time!
Most short detecting methods use fuses-blown fuse leads you to the circuit and/or removing fuses lets you check current draw. This problem only occurs with the engine running,so static tests won't help.No fuses are blown.Most likely no fuses are involved-no fuse in the car is rated to pass the current to load that alternator that heavily!There are a surprising number of unfused circuits in the wiring coming off the ignition switch. Most are not easily accessible,though there is a box (labeled 15/1) in the diagrams that seems to house two major conductors from the battery to terminals labeled 30 on the switch.These are possibly fusible links-maybe a good place to test with an inductive current meter-have to get one of those.I'm tending to suspect something weird in the electronics, possibly for the ignition since the short does not ever seem to go to ground completely (like a chafed wire to chassis would). No wires are burned-wish the thing would just go all the way out-it is hard to troubleshoot when a problem is intermittent!Been fixing electronics and cars for 30+ years,but this is an odd one!

Please,


For your sake, tighten the belts!!!


Goatman

Not a slipping belt-they're tight and I've changed them.Spraying no-residue cleaner on them (an old technique of mine) makes no change in the scream,which is coming from the back of the alternator,not the front.And the alternator is getting almost hot enough to fry an egg.Next!