Early autodimming mirrors used an electric motor to physically move the mirror up and down to control glare. Recently autodimming mirrors have switched over to using electrochromatics which has no moving parts. There are two big manufacturers of EC mirrors: Gentex and Donnelly
I chose a gentex autodimmming rearview mirror with compass and thermometer for my 98' crown victoria police interceptor.
Catch a 12volt positive lead that was hot with the ignition turned to the on position
Find a suitable place to attach a grounding screw
Find a wire that's hot when the gear selector is in reverse, i caught the BK/PK wire behind the drivers side kickpanel at C211. (For safety reasons, the autodimming feature of the rearview mirror is disabled when backing up).
Fish two wires for the temperature probe through the firewall and mount the temp probe on the underside of the front bumper
Run the wires from below the dashboard to up above the headliner where the mirror will mount
Are seven pins on the back of the mirror, the mitocorp universal harness uses only five, the two unused output pins are for connecting the rearview mirror to the outside EC mirrors.
If you do not have wiring diagrams for your vehicle, the reverse light wire is usually located in with the bundle of wires for the rest of the rear taillights and fuel pump. Are only a limited number of places to run wires from front of car to back, underside of car is not a good location for obvious reasons, nor is in between the roof and headliner. That leaves under the interior floormat, manufacturers tend to favor the edge of drivers side floor above the rocker panel since the fusebox and other required signals are located in that area. But it is possible for manufacturer to run reverse light wire above passengers side rocker panel or on top of center transmission tunnel. If you gain access to the backup light bulb sockets, there will be two wires, one is ground the other has +12volts when gear selector is in reverse. Wires are usually color coded the same at the rear of the car as they are at the dasboard.
An old glass shop to remove mirror buttons from the windsheild is to
hold a blow drier up to the mirror button until the heat from the blow
drier softens the glue and the mirror button falls off the windsheild.
If attempting this method, make sure to do the procedure on a warm day
or in a heated garage to reduce the risk of cracking the windsheild from
thermal expansion problems.
A Dealer Installed Option (DIO) from the local ford dealership:
XF2Z-17700-AA Mirror, Electrochromic/Compass With Temp. Display
F6AZ-17700-AC Mirror, Electrochromic/Compass Without Temp. Display
Aftermarket sources such as www.jcwhitney.com and www.mitocorp.com, the basic dimming mirror is $100 and the autodimming mirror with compass and thermometer is $250.
Salvage yard mirrors. EC mirrors first started to appear in vehicles in the early 1990s, ones with compass and thermometer appeared in the late 1990s. Insurance companies are not happy to declare high value late model vehicles a total loss unless substansial damage has been done to the vehicle. In serious collisions, the windsheild often shatters and the rearview mirror is damaged when it becomes airborn from the impact. To further complicate matters, many of the salvage yards that specialize in late model vehicles are not self service. Maybe you'll get lucky at the salvage yards, maybe not.
Online auction sites like www.ebay.com. Many electrochromatic mirrors appear in online auctions, going rate for a basic dimming mirror is usually around $25, dimming with compass $50-$75 and dimming with compass and thermometer $100-$150.
Are a few different mounting systems used by OEM manufacturers. Make
sure to stay away from the cam-lock style mirror mounting system used on
imports, it will not work with your vic without extensive modification.