lighted rear view mirrors

[topless82vette]

can anyone tell me which wires are which on this mirror its from a 97 gm car has three wires ... I figure I can get power to it using the sunvisors vanity mirror wires since our car doesnt have that anymore, but why did GM use three wires, I dont think its a auto dimming mirror

thanks for the help

 

[Eric]

Just a guess, but if it's anything like the one on my Monte, the third wire controls the "theatre lighting" feature. When I open the doors, the dome light and the lights on the mirror come on. The other lines are for the ground and constant power. I suppose you could disconnect the 3rd wire unless you want to route it all over creation to meet up with something else switched by the door button.