Auto - Dimming (electrocromatic) Rear View Mirror Malfunctions

[AndyF2010]

I have read some of the other posts concerning auto dimming rear view mirrors and my problem does not seem to fall into any of those.

 

2009 Fusion SE

 

Sometimes when the car is started (doesn't matter hot or cold) the auto dim will not function. I don't notice it right away because the dimmer only work if someone is behind you. The issue happens only once every month or two. Anyway, I took it to the dealer to diagnose. I went armed with cell phone videos of one day when it was not working and one day when it was. I know not safe, but I felt that I needed proof or they would just slough me off with some BS.

 

I showed the shop manager the video and he seemed convinced that SOMETHING was going on. Got a call later that afternoon and they said that they were unable to determine the cause. They stated that they checked for any TSBs and also checked the grounds, no findings. Of course it could not have happened when they had it!

 

So the next time it happened I started trying to figure out where the sensor were and manipulating them. I attempted covering the one in front, the one on top, shining a light into the rear facing ones. NOTHING! Then one day I did something very unsafe that I would not recommend anyone doing; I shut the car off when it happened the next time. Nothing happened so I started it back up and continued driving. Then I thought that I had not "cleared" the electric systems since they stay on when the key is still in the ignition (so you can listen to the radio, roll up windows etc.)

 

I again don't recommend, but I shut the car off and then removed the key on a straight stretch, put it back in and restarted the car. INSTANT auto dim!

 

Every other time that this has happened since, I have done the same thing and it works every time. The car is still under warranty so I am going to take it back and explain it, but haven't gotten around to it yet.

 

Has anyone out there had this happen and seen the dealer yet? Any ideas, other than taking it in for some kind of software glitch?

[drolds1]

I don't know what's wrong with your mirror, but shutting the car down while driving is a really bad idea for more than just the safety reasons you're apparently aware of. You're also risking damaging the catalytic converter(s). When you shut off the engine while driving at speed, unburnt or partially unburnt fuel is being drawn into the CC where the high operating temps may cause combustion. These "explosions" will render the CC inoperative, resulting in a significant repair bill.

 

I strongly advise you to cease your experimentation.

[AndyF2010]

Thanks for your reply. I suppose that I neglected to mention that I put the car in neutral prior to turning it off. I would not anticipate then causing the issues that you described. Thanks for helping

[akirby]

Thanks for your reply. I suppose that I neglected to mention that I put the car in neutral prior to turning it off. I would not anticipate then causing the issues that you described. Thanks for helping

 

 

Having it in neutral won't prevent catalytic converter problems. Stop!