OK, my dad recently pulled a rear-view mirror out of a GM truck (He thinks it was a 95). It has the compass, temp, and auto dim. He has tasked me (his little electrical engineer), to install it for him. Here is what I have.

There are 3 wires, white, green, black. Common sense and some electrical knowledge tell me that

white = 12v constant
black = ground
green = 12v switched

can anyone confirm or deny this? I really don't wanna blow up dads mirror.

 

This is the oldest year (1998) model diagram I have for the rear view mirror. Not sure if will help you but here it is.

 

thanks man, thats great...now I just gotta find a chasis wiring diagram for a 1990 454ss since dad lost his chiltons