Installing an electrochromic (auto-dimming) rear view mirror

This is the first in the how-to series on adding factory options in a w-body that it either didn't come with or never had. This is actually installed in my S10, but there isn't much of a difference.

Installing an electrochromic (auto-dimming) rear view mirror in your W-Body.

Difficulty: 2/10 (10 hardest)

This is a how to on installing an auto-dimming rear view mirror (with or without compass, without map lights) in your first gen S10. Second gen is likely the same for the most part.

Install at your own risk as this involves a little wiring work.

Don't you hate driving at night and when someone comes up behind you with bright lights and you have to flip the little lever on the mirror? I do too, so I have installed these mirrors in most every car I have owned. Even with tinted windows, those bright lights can be a pain in the eye.

What you will need:

1. mirror - most higher end GMs have this mirror, they can be had with compass, with temp, with maplights. I got mine from a 1995 Olds 88 LSS. Don't forget the connector with a little wiring! This write up involves compass and auto-dim. One day I will do a write up with map lights and temp.
2: length of wire. 18 gauge will be fine.
3. phillips screwdriver.
4. largish flat blade screwdriver
5. T20 Torx
6. wire cutters/strippers
7. 7 mm (9/32) socket and ratchet or nut driver
8. spade connector
9. soldering iron and solder
10. Shrinkwrap or electrical tape
11. beer (optional)
12. 45-60 minutes

Getting your new mirror. Look for a Buick, Cadillac, Chevrolet, GMC truck or Olds with the mirror you want.Get a GENTEX model because the Donnelly's tend to leak the fluid. They are held on by a small clip that slides over the button on the windshield. Take the flat blade screwdriver and go up under the base and GENTLY pry between the glass and the mirror base while wiggling the mirror towards the top of the car. Most junkyards charge $5-35 for these. Depends on where you go. Or you can find them on ebay.

Take off the old mirror in your truck. Most are just your standard day/night.
But many first gens had map lights. There is a set screw holding it to the button. Generally it's a phillips or a T20 TORX. Remove the mirror.

If you had the map lights, there's a connector you need to unhook.

Take your phillips screwdriver and remove the three screws holding the driver's sunvisor. Unplug the connector to that if you have the vanity mirror and set aside.

Now, take the two screws holding the A PILLAR trim and gently pull it off and set it aside. Also go ahead and pull off the under dash cover to get to the steering column and fuse box.

Now you're ready to install the new mirror. Oftentimes, when you pull one of these mirrors the clip that holds it on to the windshield button gets all fubar'd and the mirror will be loose. I'll either use the base from the old mirror OR take the compass off and drill a hole in the base for a set screw from the old mirror. The latter is the easiest and once you reinstall the compass, it disappears.

But, first thing is first. You need to run some wiring. You can't use the original harness for the map lights except the ground. The ground on your new mirror will be NO. 2 on the connector. No. 1 - far left in pic, yellow in color, some are different colors - is ignition and will go to the fuse box. No. 3 will be for the reverse light switch - this is optional and will be covered in a few. So, tie into the black wire on the original connector or if you don't have this, run a wire to the a-pillar and drill a hole in the metal and run a screw in to tie down the wire and ground it. Never mind the other wires, these are for DIMMING SIDE VIEW mirrors...Another project for another how to coming later.

Now tuck the map light connector up in to the headliner as it won't be needed and possibly return the truck to stock if you desire some day. Of course, remember to wrap your splice in shrinkwrap or electrical tape. Now run a wire from No. 1 in the connector, tuck it in to the headliner and run it down to the map light or dome light wiring and take it to the fuse box. There's an empty space marked IGN and cut the wire to length, add the spade connector, solder, shrinkwrap, tape and plug it in to the IGN.

(OPTIONAL) Now, run the wire from the No. 3 (green) on the mirror connector with the ignition wire down to the STEERING COLUMN, find the wire on your neutral switch for the BACK UP LAMPS, on my truck, it is LIGHT GREEN. Splice in to this. What this does is disables the auto-dimming when the truck is in reverse. Useless to me though. Leave it unhooked if you desire.

Install your mirror on the windshield and tuck the wiring harness up in the headliner and route it using the cover if you got one with the mirror. Taking care not to damage the harness, reinstall your sunvisor, a-pillar trim and underdash trim.

If you have the COMPASS, you will need to calibrate it. To do this, look up at the bottom of the mirror and find the calibration button, to push it in, you will need a straightened paper clip. Press the button until the display says "C", then drive in a complete circle until a direction is shown in the display. Now, with the ignition on press the button for 3-4 seconds and it will generally say "8", this is the zone for the compass. press the button until the number 6 is shown. This is the zone for TEXAS.

You're ready to enjoy safer night driving! Also, if you have the compass, it is easier for you to find your way.