Rear view mirror auto dimming/anti-glare test ?

**b206** · 10-11-2013,02:35 PM

Hello,
Now that winter is starting to set in I'm noticing a view issues with my 2009 A4 - the main problem being the auto dimming/anti-glare rear view mirror and side mirrors which don't seem to dim.
I have privacy glass which I understand can cause problems - but how do I test the rear view and side mirrors ? I've tried flashing a light at the mirror and covering the rear sensor up but nothing seems to activate the anti-glare.

Any tried and tested methods ?

Cheers.

**Guest 2** · 10-11-2013,02:37 PM

How do you know you have autodimming mirrors? I know they came with RVM but the wing mirrors themselves were an optional extra I think.

Do your wing mirrors have an line running along the edge of the glass?

Welcome to VWAF

**b206** · 10-11-2013,02:40 PM

Hi - I checked the option codes which say I have auto-dimming and heated side mirrors. Also have the line around the edge.

**Guest 2** · 10-11-2013,02:47 PM

I assume the green light is on when you're doing the test on the rvm?

Is the privacy glass factory fit or aftermarket film? Could you not ask someone you know to drive behind you with their full beam on at night?

A fault scan would show if anything is wrong.

**b206** · 10-11-2013,03:10 PM

Yep, green light is on - factory fitted tint.
When driving at night it doesn't seem to work when cars are behind, I've been told the tints can prevent enough light hitting the sensor so the mirrors don't dim to the same degree as vehicles without tints.
To be honest the rear view mirror isn't too bad as the tints block most of the light - would be useful if I could get the side mirrors working though.

The rear mirror has a sensor at the back which I'm guessing tells the mirror when its dark - it looks like there is a sensor to the right of the on/off button which must detect headlights from behind. I was hoping you could block the rear sensor (which will tell the system its dark) and shine a light into the front sensor (headlights), but it looks like the system is difficult to fool?!

**Guest 2** · 10-11-2013,03:19 PM

They only dim when the car behind has full beam on, dipped beam is fine and it won't pick it up.

I noticed this on the loan A8L I had which had the wing mirrors too and they didn't dim until the full beam from the car behind was on.

**b206** · 10-11-2013,04:01 PM

Ok, thanks, that would explain.
The passenger side mirror doesn't heat up either - just viewed a thread below this one. An anti-glare replacement mirror is 4 times the price of the standard one with heater, makes you wonder whether its worth it!

**sportq** · 11-11-2013,11:07 AM

I have the auto-dimming rear view mirror and honestly I think it's broken. I had one on a Mondeo many years ago and it was much more responsive, any lights behind in the dark would trigger it. The one on the Audi does work but it's erratic, most of the time it doesn't appear to do anything then I'll glance up and see the green tint is working. Is there a way to adjust the sensitivity with VCDS?

Peter