Right around that year, GM decided for some strange reason to flip the
alternators plug's pins. One is the excite wire that 'turns on' the
alternator. I would swap pin one and two in the white plug to see if
that turns it on.

I have seen this happen a few times.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
Canadian Off Road Trips Photos: Non members can still view!
Jan/06 http://www.imagestation.com/album/pi...?id=2115147590
(More Off Road album links at bottom of the view page)

CGBear wrote:
>
> I have an alternator that has been checked out at the local Autozone,
> it passed...it's good.
> But I installed it in my car, A 1987 Firebird formula, and it doesn't
> charge. I disconnected the battery output and used a test light on the
> output, and nothing. There are 3 wires plugging into the alternator, I
> know the first wire is power, the second goes to an idiot light, where
> does the third wire go??