Adding an auto dim rear view mirror

May 09, 2016, 06:57:09 PM

I've grown to really like the auto dim rear view mirror in my 1991 Lincoln Mark VII. The 90-92 Mark VIIs had a modern style electro-chromatic auto dim rear view mirror as an option, replacing the goofy 84-89 mechanical auto dim rear view mirror. It's great at night as you don't have to flip the little tab below the rear view mirror when someone with modern ultra bright headlamps is driving behind your car. Plus the mirror has a range of dimming ability instead of just "on or off" like the factory manual mirror in 83-88 Thunderbirds/Cougars. The other nice feature is that the 90-92 Mark VII auto dim rear view mirror has a mounting tab for the factory headlamp dimmer sensor.

I was able to procure the auto dim rear view mirror from a 1990 Mark VII and install it in my Thunderbird. It was a pretty easy exercise. Make sure you get the mirror connector plug otherwise you're SOL on connecting the mirror. Looking at the back of the mirror the connector has three wires.

Left to right the wires are: power, ground, and reverse off. Obviously the power wire is connected to a 12V switched ignition source and the ground is, well, connected to a ground. Those are the only required connections for the mirror to function. The third wire, reverse off, turns the mirror off when the car is placed into reverse. This wire is optional as the mirror will function without it connected. To have this function work you have to connect this wire to the backup lamp power wire.

So once you make a couple connections you can have a modern electro-chromatic auto dim rear view mirror that works with the auto headlamp dimmer sensor. It looks factory as well because it was factory fitted to Lincoln Mark VIIs. I really like this simple modification.