Auto-Dim Compass Mirror install
Last weekend, I installed an auto dimming compass mirror in the B5:
I would rate the install a 2-2.5 out of 5 - not all that hard.
First off, there are several auto-dimming mirrors out there, most made by a company called Gentex, they seem to be the OEM supplier for most brands.
The most important (if you are installing into a B5) thing is that it has the common twist-lock mirror mount like this:
If the one you get does not have this mount, you will have a hard time fitting it.
The part # for the one I installed is E11015313: Note - if you buy one of these from Fleabay, make sure it has the VW twistlock mount - the BMW version has the same part # with a different mount!
Mine came with the little covers to hide the wires
4B0857511 - Windshield side
And 4B0857593 - Facing inside (Wire channel)
installing the unit to the windshield is pretty easy - turn the old mirror base 90 degrees clockwise.
Note - Do not apply force in any other direction other than rotation. if you shift/pry/lever/manhandle/lean on the mirror, you can crack your windshield. If you only rotate the mirror base around an axis perpendicular to the glass, you will be fine.
You have been warned.
If you are not sure even after the above, hit up youtube - lots of videos there showing how to do it.
Once you have the old mirror off you install the new one in reverse - mount it 90 degrees to the regular position, and while keeping the base flush to the windshield/base, rotate counter clockwise until it locks in place. Same warning as above applies.
Electrically there are six wires going into the mirror. If all you are interested in is the compass and the dimming, then you only need to connect two of them - #'s 1 and 2. These were white and black in my mirror, respectively (bottom right in this picture)
I connected the black wire to the 10mm nut next to the sunroof motor (loosened nut, stripped wire and placed underneath, retightened).
To get at the nut, I gently pried the sunroof cover down with a clean slot screwdriver. To run the wire from the mirror to the nut, I temporarily removed the little 6" visor between the mirror and the sunroof controls - it comes free with one Philips screw in middle of the visor.
For power, I originally hoped to find switched power in the sunroof, but could not find anything reliable, as the sunroof goes through the power retention module that keeps accessories powered until the key is removed.
I ended up running a wire from the mirror across the headliner (tucked in) down the A pillar, tucked between the A pillar and the dash, down to the fused side of the blower fan fuse (hot in key-on).
That got me power and ground and a functioning mirror.
looking through a number of other threads, the remaining wires are for left and right dimmable outside mirrors, door pin and reverse.
The reverse connection is to un-dim the mirror when going backward, but I have not found that I need it, so it remains unconnected.
For the dimming, the mirror works great - dims at night just fine, even through the darkish tint in my rear window.
For the compass, it is self-calibrating, but you may need to set the zone depending on where you drive: (I am zone 10)
There is a recessed button on the bottom of the mirror:
To check / set the zone, press and hold it for about 5 seconds (I used a toothpick), and a number will appear in the display. That is the number of the zone the mirror is calibrated to (mine was zone 8, must have come from a car in the mid-west). If you are in a different zone, release the button, and keep pressing the button again until your zone comes up. stop pressing the button for 5 seconds and it will lock in that zone.
That's it - enjoy and post up any questions.