Hey Guys,
I just finished an LT1 swap and, after starting the engine and looming the wiring, I realized I'd forgotten to connect the alternator to the instrument panel. I looked at some wiring diagrams and it looks like that if I don't hook that up, the alternator charges constantly. Is that correct, and if so will it cause any problems? It a race car so it basically never idles around or has it headlights off. I'm really hoping to avoid having to mess with the wiring looms again.

 

Thats the wire that powers up the alternator. With out it, it usually will not charge. If i remeber correctly

 

Drat. I was afraid of that. Do you happen to know what pin on a 3rd gen instrument panel it's supposed to go to?

 

Not off hand but I can take a look at the schematic later when i get home. If you remove the dash , and trace the printed circuit you can easily trace it back to the gauge, and or charge light. Its just a 12v switch power.

 

So it connects to the charge gauge? Should it be on whenever the car is?

 

Well If i remember correctly, when the key is turned on it sends 12v to the alternator to energize the field. When the alternator then spins and generates electricity and sends the voltage to the gauge/ or light. When the alternator is not charging that wire is at a ground potential and illuminates the light.

Don't quote me on this too much, I really need to see a schematic to know what is really going on, but this is what i seam to remember or something close to it. lol

 

Two types of LT1 alts, single wire and two wire

Single wire:
Tee into the fan relay 12v fuse and put a 470ohm resistor inline. 12v on the exciter wire will burn the alt up in a few weeks. Only wire will be on pin L

Two wire:
Same fan fuse wire splits into two. Alt pin F gets 12v switched, pin L gets the resistor inline. Again, 12v to both pins will burn the alt up quickly

 

^^^ Thanks for the correction, Its been a while since I wired me dash (13 years).