i need help with installing a rear view mirror in my 87 iroc it does not have one now,but i bought a auto dimming mirror for it and i have no idea what the 3 wires hook up too!!please help thank alot craig

One's ground, I'm sure of that.

One's probably constant power and the other's gonna be switched power.

By doing that the switched power is going to turn on the map lights, but there must be a photocell right? That needs constant power in order to work.

Unless it's got a relay that tells it when you have the headlights on or off.

I don't know. I'm shooting in the dark. Pun intended!!!

Those are the only two possibilities. You'll have to run it each way to see for sure. Try just hooking it straight to the batt. before you put it in. That way you can label the wires after trial and error testing.

You will most likely have a) a ground wire, b) constant 12v, and c) 12v switched by the door switch/dimmer. Cant help you with identifying them however. Good luck!

The wires are Ground, Switched Power and Reverse. When you put the car in reverse, the mirror will never flip.

Well that's assuming that it has map lights on it. If he would reply back to us then maybe we'd know.

You mean it will never fade in reverse? I didn't know that. Cool.