I've just realized my Alternator connector has 2 wires. A red and a Brown/White. The brown/white is where the red would be on an Fbody harness. Anyone know what this other wire is for? It's a 14ga red.. I'm guessing the harness I used on my LT1 swap may have been out of a B-Body or perhaps a Y-Body ?

 

Here's the wiring diagram for a 95 F-Body (since you didn't give the specific year of your car). There is one large gage red wire and one small gage red wire. The small gage red wire is the power to the voltage regulator.

http://shbox.com/1/starter_charging_95.jpg

https://www.camaroz28.com/forums/lt1...nature-879835/

 

Thanks, already had the Fbody wiring.. I was trying to figure out what the extra wire was for. I have no idea what year the harness is.
I did my swap 10 years ago and I'm making some changes and I stumbled upon this. I had it wired wrong but it still worked. I've rewired properly and I'm still good but I was just curious why this wire was there.
Alternator connector has pins S-F-L-P
L- is the 12v with 470ohm resistance as seen in the fbody charging circuit.
S- is the unknown 14ga red wire. It has 0v when car is running and charging using my 94-96 vintage fbody alternator.
F- is the Brown/white which I had wired up in place of L and the car charged and worked great for 10years.?

On an fbody harness pin L is red 18ga.. nothing in S/F/P
My connector is Red14ga at pin S and brown/white 18ga at pin F and nothing in L/P

 

Corvettes have the wires like you described, except they usually also have the L wire. The S wire is for remote sensing of the voltage, closer to the main load (fuse box?). If left unattached, the alternator just uses local sensing, at the other terminals. The L wire should be switched ignition voltage.

 

Thanks
for anyone ever searching this, if you wire 12v with 470ohm (which is sometimes not required depending on where the 12v comes from) to pin F, it works fine and the larger pin S wire is not required.
Fbody plugs only have the 1 18ga red wire on pin L which also requires the 470ohm resistor and 12v