I have a 91 Firebird. Recently the altenator was fried and the wires started on fire. The connector GM gives you has three wires comming out of it, a bigger red one, and two smaller diameter wires, a black one in the middle and a brown one on the other side. However there are only three wires in total that go to the altenator from the car's wiring harness. The insulation is burnt off, but they are still intact. There is a big red one that obviously goes to the lug on the back of the altenator, another big red one that obviously goes to the red one on the connector, and a small black one. There is no small brown wire comming from the car. To which wire on the connector do I connect the black one? Also what do I do with the left over wire?

 

The small wire from the engine harness should be brown - maybe it's too charred to recognize. The brown wire from the engine harness goes to the "F" terminal on the connector (it may be marked "I" on the alternator). The "F" terminal is the terminal next to the large red wire terminal in the plug.

Tim

 

So the brown wire on the plug (the one on the outside) isn't used in this particular year Firebird? Cover it up with electrical tape and let it hang I guess. I hope your right, I'd hate to wreck a $130 altenator.