Exterior Mirror Dimming

[boosted-fc3s]

Hey All,

Pretty sure I read in the manual that the exterior mirrors are electrochromatic and dim when the inside mirror dims. I have a question regarding that. I actually got the car with an aftermarket audiovox mirror with a backup cam, temp, and compass in it, replacing the oem auto dimming mirror and homelink buttons. They added seperate home link buttons where the sunglasses go. Does the exterior mirror dimming depend on the interior mirror? Ie by replacing it, did they kill the exterior auto dim? Anybody know.

[inov8]

Yes, both the interior and exterior rear-view mirrors are electrochromic and dim/tint automatically.
The sensor for auto-dimming is mounted on the interior mirror, which in turn controls the exterior mirrrors.
If someone indeed replaced the interior mirror with an aftermarket one, they effectively disabled the EC exterior mirror function.

Source of information: 2005 Avalon technical features manual, page BE-192

[boosted-fc3s]

Guess its time to acquire and OEM mirror and tear it apart and play Electrical Engineer for a while and see if I can get the sensor to work.

[inov8]

Here are the wire colors according to the 2006 factory wiring diagrams. Chances are good this was not changed in 2006 or 2007.

Ignition - yellow
Ground - white / black stripe
EC+ - Black
EC- - White

EC+ and EC- are wired to corresponding terminals on the exterior mirrors.

[boosted-fc3s]

Hmm, wonder if I can just build a little circuit with a photocell to trigger it rather than blowing money on a whole oem mirror to tear apart.

[inov8]

The bigger challenge would be to figure out what sort of signal has to be applied to the EC+ and EC- terminals. Is it AC or DC; low voltage or high voltage? Perhaps an internet search for Gentex patents would yield some clues.