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??
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 >
I'm assuming that this is a 10SI, the third wire parallels the battery wire, it is there for remote voltage sensing. it should have +12V on it even when disconnected from the alt.
nate
I'm assuming that this is a 10SI, the third wire parallels the battery wire, it is there for remote voltage sensing. it should have +12V on it even when disconnected from the alt.
nate
Should the alternator still charge even if the wires aren't hooked to the regulator? Or do you have to have one wire with power going to the regulator?
You need all 3 wires hooked up. That is the reason they put 3 wires on it.
One feeds the battery power, one senses voltage level and one 'excites' or turns on the alternator's magnetic field.
Folks can make pretty good trail arc welders by bypassing the regulator on those alternators..... I sure wouldn't want that feeding my battery or electronics.
Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail >I got a wiring schematic from a buddy that has the Alldata programs. It rained a bit today so I'll hopefully get it figured out tomorow morning. Thank you for your input.
Just remember they switched pin one and pin two on the smaller plastic plug in the mid 80's. Hooking it wrong won't hurt anything, it just won't charge.
You can even see the pin numbers stamped on the case and on the plug.
Mike
CGBear wrote:
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