View Full Version : 92 to 89 rear view mirror help please.

01-15-2017, 01:20 AM
So the short of it is:
A four pin on the 89 wiring harness (no sunroof) to control the motorized mirror autodim. 92 is electro-chromic. 2 pin. Have studied pages 188/189/35/15 of the 89 EVTS manual.
Need to build a jump cable from the 4 to 2 but know not what the 92 mirror wants on it's two pins.
A source for these connectors would be great as well. Don't like hacking anything.

sam jones
01-15-2017, 12:50 PM
Good morning

The four pin connector pictured is for the separate Head Lamp Dimmer Sensor located at the base of the mirror. It appears you do not have one. The three connector attached to the mirror will power the auto day/night feature. For your mirror you will need a year specific electrical wiring and vacuum diagram for the pins connector functions and possible jumper. The wire functions for 1989 are as follows:

- (G) Black. Ground circuit.

- (F) Black. Rheostat to sensor.

- (E) Black. Amplifier to rheostat.

- (D) Black/White. Dimmer switch to dimmer amp.

I would think (G) Black Ground and (F) Black Rheostat to sensor are needed if your GENTEX unit has the integral Head Lamp Dimmer Sensor feature. Maybe other members have more information on this subject.

Good Luck.

01-15-2017, 02:39 PM
Thank you very much for getting me steered in the right direction. This mirror does have a forward facing photo sensor.

How did you find the wire functions? I see the connector on page 136.

Off to search for photo cell testing and source for connectors.

01-15-2017, 03:34 PM
You don't need to per se.

It's plugged in, it'll work fine as an auto day/night mirror if the photosensors and electronics are working.

The extra two pins were probably for electrochromic rear view mirrors on the doors; the MN12 never offered that option.


01-17-2017, 03:18 AM
Here is what I have found so far. Mirror went on the bench. Under bright light you can see the factory pinouts through the connector holes. This is a Gentex GNTX-101.

Feeding it 11 VDC through the 3 pin incoming. Rewarded with the control switch lighting up and the mirror auto dimming. The Fluke 87 multi meter was cranky so with the Cen Tex standby get a constant 1.39 VDC when the *REAR* facing photo cell was lit up out of the 2 pin for auto headlight dim.


01-17-2017, 10:10 AM
The 2 pin isn't for headlight auto dim, I don't think ... it's supposed to be for electrochromic outside rear view mirrors.

Here's an article describing some of the variations on the GenTex rear view mirrors: http://www.the12volt.com/installbay/forum_posts.asp?tid=8560&tpn=7


01-17-2017, 04:49 PM
You are correct. I was tired and turned around last night. The 1.39 VDC is coming from rear photo cell. Can't get a trigger off the front facing. Oh well. Back to the "want to buy section. Thanks for the help.

*Edit* Just bought the correct Rube Goldberg affair. Hope plug and play.


01-21-2017, 08:02 PM
Great service from Classic Cars Unlimited. Correct 1989 mirror arrived in two days. Part numbers are the exact same on both but the mount foot is considerably different for the front facing sensor.

Would have to cut the case but suspect a smaller front sensor could be added. One thing off the checklist.

01-21-2017, 08:26 PM
Duplicate post. Mods please remove. Thanks

01-21-2017, 10:13 PM
Looks like the mirror I had in my 89 Continental with the Autodim feature.