ok i just installed a megasquirt so i changed all my wiring. when the car is idling im seeing more then 15V at the battery. now we have hooked up the main (B) terminal (the one with the red boot and nut) to the fuse block, then we wired the (s)terminal to the fuse block as well and left the (L) terminal unhook as the Manuel says its just for the check battery light so my question is do i still need that L terminal to make the system work?

 

ok so i have readed the wireing diagram on the alt and found that the L needs to be wired to a light so i wired a light to power and to the L terminal start that car and voltage is the same light does go out once i start the car tho... could i have fried the alt by not using the L wire

 

Sounds like the voltage regulator is not working correctly. You should be at 14v with the engine running. Remove the alt, and take it to a parts department that will test it for free just to be safe.

 

ok called a guy up. looks like all i need that L for is to see initial voltage then it will triger the correct voltage so all is well

 

Yeah high voltage means bad voltage regulator or the connector to the voltage regulator (located inside the alternator) is unplugged. I'm guessing that's the L plug you're talking about.