Had the creeping black gel invading my Donnelly rearview mirror, did some research on this site and others and swapped it out for a Gentex 177 GNTX-177 pretty easily. $30 used + plus shipping for the mirror, pigtail and temp sensor. The 177 has the proper Ford wedge mount, and includes compass and temp function. The old mirror slid right off the mount and the new one went right into its place very easily.

http://www.ebay.com/itm/Gentex-GNTX-177-Autodim-mirror-with-compass-temp-Dodge-Toyota-GMC-Ford-universal-/142102309281?_trksid=p2047675.l2557&ssPageName=STRK%3AMEBIDX%3AIT&nma=true&si=H6HkeUVwf8XDP%252B6reu95DdC9yMc%253D&orig_cvip=true&rt=nc
The wiring is the one item I had to do research on, as the existing connector is a 3 wire and the Gentex is a 7 wire. The good news is no splicing or cutting should be required, because you can easily remove the leads from the old 3 wire connector and push them into the new 7 wire connector (remove the cut ones from the donor vehicle first!) as they all match right up. They are even in the same order (pins 1-3) It is very easy to do this, just push down the metal tab and pull out the back of the connector. Swap them out one at a time into the 7 pin connector, install the mirror, plug the connector in the back and you are all set.

Pins 1, 2 and 3 are direct swaps for each other and the functions are identical. I removed and eliminated the wires which were slotted in pins 4 and 5 as they were intended for auto dim side mirrors. Pins 6 and 7 are for a temp sensor, seeing as Ford already provided one in the overhead console I mounted the sensor inside to measure cabin temperature.


Pin # 7 Pin 3 Pin Description
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Pin 1 12V+ 12V+ Keyed Power (+)
Pink replaced with Blue/Pink Stripe
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Pin 2 Ground Ground Chassis Ground (-)
Black replaced with Black
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Pin 3 Reverse Signal Reverse Signal Positive lead from the reverse lights* (+)
Green replaced with Black/Pink Stripe
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Pin 4 Auto Dim N/A Outside Side Mirror
Gray
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Pin 5 Auto Dim N/A Outside Side Mirror
Pink
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Pin 6 To Temp Probe** N/A
Green /Black Stripe
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Pin 7 From Temp Probe** N/A
Black
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*Note: Pin 3 should be connected to the backup lights to turn off the auto dim feature in reverse. If you dont want to use this connect the wire for Pin 3 (green) wire to chassis ground. If this pin is open the auto dim will not work properly.

** You will need wire depending on how far you want to extend the sensor. (if you even use it at all)

It’s a very quick cost effective way to swap out the OEM mirror, I would recommend that if you get one of these ensure you get the pigtail harness and the 7 pin connector or it will be a lot of work to splice everything in.

 

I would have just stared at the wiring going "Crap!"