Gm Delco alternator question
 

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??

Gm Delco alternator question
 

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??

Gm Delco alternator question
 

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??

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

Gm Delco alternator question
 

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??

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

Gm Delco alternator question
 

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?

Gm Delco alternator question
 

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 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:
>
> 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?

Gm Delco alternator question
 

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.

Gm Delco alternator question
 

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:
>
> 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.