W126: Outside mirror mis-wiring
 

My tech called me today with an interesting problem: one of his customers had a broken right side (passenger) outside mirror.

Simple enough! He ordered a replacment and it didn't work! So they gave him another one: same story! So he notified his part man at Mercedes of San Diego who, in turn, went back to New Jeresy for techical help. No soap!

So here's what I found. The new units are wired 'wrong' if you use the older mirror as a guide. It's from an '83 300SD.

When the NEW part is installed the mirror will only move in just one direction.
http://pages.prodigy.net/jforgione/mvc-844f.jpg
As you can see, the motor wiring is identical on both, so the connector wiring should be also!
http://pages.prodigy.net/jforgione/mvc-845f.jpg
To fix the wiring (without re-wiring the car), do the following:

1) Remove wires in pins 1, 3, and 4 by releasing the holding pins.
2) Move the green wire to pin 4
3) Move the white wire to pin 1
4) Move the black wire to pin 3

That fixes it! Of course, you need to take the mirror assy apart but that's easy. Remove the mirror by releasing the spring: then loosen the screws to remove the back aluminum assy. Peel back the protective covering over the pins.

Hope that this helps some W126 owners.