# Auto Dimming Rear View Mirror



## aTTkinson (Oct 22, 2018)

Hello there.

Newbie here, having just purchased a 2010 TT Quattro.

Having owned A3, A4 and an A6 I am surprised at the lack of goodies on my TT. All the above had auto lights, wipers and auto dimming mirror. OK, the above cars may have been S lInes, but the TT does have the luxury of heated seats, the lights package, heated wing mirrors and a few other bits, but I'm surprised that in this day and age, and on a vehicle this expensive, the autodim mirror isn't a standard feature. I've skimmed through a couple of the threads on here on this subject, but can I ask................ is retro fitting viable? I heard sometime in the past that the wiring for the goodies listed as extras are is fitted in the build, but not used ("saves fitting various looms, keeps it standard" was the explanation). Is this true? If this is the case, has anybody fitted a autodim mirror?


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## qooqiiu (Oct 12, 2007)

Pretty much everything can be retro fitted. I think someone has done it on here. Member MT-V6 perhaps?

Unless you can source the 3 mirrors used then the cost will be hefty. The wing mirror glass is about £700 and the rear view is a few hundred new as well. Then there's the looms to consider. They're gonna be £70 ish each I'd imagine.


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## pcbbc (Sep 4, 2009)

aTTkinson said:


> but I'm surprised that in this day and age, and on a vehicle this expensive, the autodim mirror isn't a standard feature.


I am afraid this is becoming the norm with the premium manufacturers. Lower base prices, but all the knobs you'd expect are cost optional extras.

I notice it has been getting worse also. On the MK3 even climate control (vs manual non-temperature controlled aircon) is an option, as is the wind deflector on the roadster. These things were all standard on the MK2 (and I expect MK1 also).



> Is retro fitting viable? I heard sometime in the past that the wiring for the goodies listed as extras are is fitted in the build, but not used ("saves fitting various looms, keeps it standard" was the explanation). Is this true? If this is the case, has anybody fitted a autodim mirror?


Yes, I believe it is possible to fit the dimming mirror.

Contrary to what you might think or have been told, wiring for options is not always fitted. Fitting every wire and connector to base models would be quite expensive, so it would outweigh any cost savings from standardisation. So looms are at least semi-custom to the build requested.

I have no idea if you will be lucky with the mirror. Most of what it needs (power and CAN I expect) are likely to already be there for the courtesy light. So it may not be that hard to retro-fit. Sorry I do not know for certain.


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## ReTTro fit (Nov 9, 2014)

The looms WONT be in the car but is easy to add 
Run wires from bcm to mirror and from mirror to each door 
The rear view mirror needed can be gotten off eBay for a reasonable price, the side mirror glass are extortionate !

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## qooqiiu (Oct 12, 2007)

If you decide to go down this route I have a pair of auto dimming glass that id sell.


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## r_turner01 (Sep 12, 2018)

My TT appears to have tinted mirror glass on the doors, not sure if that is the case on all models but they are certainly not clear, but I dont have autodim mirror, car did come with factory tinted glass tho so not sure if I would need the autodim rear mirror but would be a nice touch as my Ibiza has factory tints and autodim, could you just fit the rear view mirror without the door glass or is it an all or nothing as canbus will have a fit otherwise thing?


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## MT-V6 (Jan 11, 2015)

I fitted the dimming rear view mirror and wing mirrors. The dimming mirror also has space for the rain/light sensor so I fitted that too.

Not a particularly hard job but there is a reasonable amount of wiring to do. I have written guides for both in the KB.

However, a new windscreen is required.

Dimming rear view is required for the wing mirrors as it uses the same sensor, but you can fit the rear view without the wing mirrors

The wiring looms are very customised and there must be many variations as I have found nothing spare on the TT for any of my retrofits

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## Romani44 (Jun 14, 2018)

Hi all,

The autodimming feature has stopped working in my car. Is it a case of replacing a battery? Or are more extensive works required?


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## IPG3.6 (Sep 5, 2015)

Mine has also stopped working (no more green light)

- have checked all wiring and plugs - they're ok
- have tried holding the button down and waiting 
- checked all fuses (guessing it's connected to the interior light fuse)

But still dead. Not sure what happened to make it stop.


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## MT-V6 (Jan 11, 2015)

Romani44 said:


> Hi all,
> 
> The autodimming feature has stopped working in my car. Is it a case of replacing a battery? Or are more extensive works required?


There is no battery, so first thing to check would be whether it is receiving power

Weird for two peoples to stop working at the same time though


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## SwissJetPilot (Apr 27, 2014)

From workshop manual *General Body Repairs, Interior; D3E80079BA4* -


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## meteor (Nov 4, 2012)

qooqiiu said:


> If you decide to go down this route I have a pair of auto dimming glass that id sell.


To make it complete I have an extra auto dimming mirror 8J0 857 511E 4PK and mirror covers 8j7 857 593C (for TT convertible) and 4F0 857 593 J (for coupe).

BR, meteor


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## Llewkcalb (Jul 15, 2019)

One thing to consider is how good the mirror is when combined with rear tints.

My rear windows are tinted and I thought my mirror was broken. It works fine, it just seems to work less effectively due to the rear tints.

Due to windscreen and parts you may feel a bit underwhelmed for cost after install.

The side ones sounds sound great but cost alot.

Steve


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## IPG3.6 (Sep 5, 2015)

SwissJetPilot said:


> From workshop manual General Body Repairs, Interior; D3E80079BA4 -


My green light is definitely off all the time.


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## IPG3.6 (Sep 5, 2015)

after a bit of an hiatus I have my FrankensTTein back and enjoying driving him around again!

...so randomly. I saw the green light come back on for one drove. Parked up and got some groceries, jumped back ibto the car to see - it was dead again!!! Hmmmm...









I had it touched it or anything for either change to occur. Hahaha


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## Romani44 (Jun 14, 2018)

IPG3.6 said:


> Mine has also stopped working (no more green light)
> 
> - have checked all wiring and plugs - they're ok
> - have tried holding the button down and waiting
> ...


Did you ever manage to resolve?


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## IPG3.6 (Sep 5, 2015)

I still haven't had a chance to look more into it with other things "getting in the way"

But i did notice that one day it was green light on. then the next drive - not on again :lol:


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## Graham'sTT (Dec 6, 2014)

Just a question:
Is it programmable via VCDS - does any-one know?
The reason for asking is that I had a 2003 VW Golf with auto-dimming rear view mirror. This could be switched on and off with the button on the mirror.
Yes the TT (with auto-dimming mirror) has a button for on and off, but on the two TTs I've had, if you turn off the mirror, it automatically comes on next time the ignition is switched on. On the Golf it would stay off until you operated the switch on the mirror.
Could the 'fault' be that the coding is different?


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## IPG3.6 (Sep 5, 2015)

I don't think it would be a coding thing as coding is either set or not. 
It wouldn't be intermittent as some of us are experiencing.

I think it's a wiring thing. I just haven't prioritized it lately. Will do so soon enough.


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## SwissJetPilot (Apr 27, 2014)

There's a User Manual specifically for the mirror in the KB along with a section in another the Workshop Manual that covers it. Otherwise you may want to check your Owners manual as the setting are probably covered there.

I know there are fault codes for the external wing mirrors, but no idea what comes up for the auto mirror. Would be interesting to know...

Any chance you guys could unplug your auto-dim mirror and see if it kicks up a fault code?

*Section 1 - Body & Interior
1.5 Body Interior (D3E80079BA4)*
https://www.ttforum.co.uk/forum/viewtop ... 1#p9331737

*Section 2 - Electrical Wiring Diagrams, Communications and HVAC
2.5 Internal Rear View Mirror with Auto Dim and Compass*
https://www.ttforum.co.uk/forum/viewtop ... 3#p9331743

If the mirror has power with green light and the wing mirrors dim then it sounds like an internal fault in the rear view mirror. Technically a sealed unit but others have opened them up as shown in this *link* by *IPG3.6*.

Try holding your finger over the sensor that faces out the windscreen, and shine a torch into the one next to the button. After a few seconds it should dim


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## MT-V6 (Jan 11, 2015)

It is not codeable, there is only power to it, no canbus, linbus etc. All the electronics are self contained. Just a reverse signal from the cecm to undim when in reverse

So the difference to the golf must be the internal design of it

It uses dash fuse 7, FYI


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## IPG3.6 (Sep 5, 2015)

Bringing this thread back to life - mine i still not working.

I have tested the connector pins with a multimeter and it is receiving 12v on IGN on so i know my wiring to the mirror is OK. The connections at the plugs are OK so that leaves internal wiring as the culprit.

It seems the green light does turn on randomly (i've noticed it tends to happen on hot days) so there must be something inside, a contact, a trace, or something that has failed but can make the contact for the power light to come on. I notice that when the green light is on the dimming doesn't function.

I was trying to figure out a way to dismantle the unit to get to the connections after the 6 pin plug (only of which 3 wires a connected - power, - ground, - reverse light signal) but i think i would have to break it. Which is not ideal.


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## MT-V6 (Jan 11, 2015)

Do you mean that you want to open up the mirror casing or just the plastic trim over the mount? It doesn't looks easy to open up

It definitely sounds like the mirror is the problem though


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## IPG3.6 (Sep 5, 2015)

So to inspect it looks like you'd have to somehow open up the "base" where it mounts onto the window but i can't see how one would get to the origin of the 6 plug wires unless you break that pivoting joint.


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## MT-V6 (Jan 11, 2015)

Agreed. I think the cover over the mount must pop off somehow...but all the wires go through the ball joint. Not sure if the balljoint can be separated without breaking it?


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## 237tonybates (Jan 26, 2013)

Sont know this helps but ive done some mirror module transplants in the mqb mirror . Here's a photo of said area









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## IPG3.6 (Sep 5, 2015)

237tonybates said:


> Sont know this helps but ive done some mirror module transplants in the mqb mirror . Here's a photo of said area
> 
> 
> 
> ...


did you have any more insight as how you went about dismantling the housing to get to that end of the wiring?


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## Audi Russ (Feb 29, 2020)

One other thing which I don't think has been mentioned yet, if you want auto lights you may well need a new windscreen as it has the sensor built into it.

I had a new windscreen earlier this year and as my car doesn't have the auto lights option the windscreen people said it was actually more difficult to source a TT screen without this feature as most cars have been specced with it.


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## IPG3.6 (Sep 5, 2015)

Thanks @russ. The car is wired up with autolights/rain sensor installed already so it is not missing it's dependancies to work.


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## SwissJetPilot (Apr 27, 2014)

Vehicles with ADAS require special OEM glass designed specifically for these features and require re-calibration if the windshield is replaced. I had to have this done when I replaced the windshield on my 2015 Tiguan which has adaptive headlights, auto dim mirror and lane assist.

However I'm not sure an ADAS type windshield is necessary for the auto dimming mirror feature on the Mk2 TT.

@ *MT-V6* - From this previous post, you have the non-ADAS type windshield, and yet your auto dim still works okay, true?

*Windscreen Replacement*
https://www.ttforum.co.uk/forum/viewtop ... &t=1873725


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## MT-V6 (Jan 11, 2015)

I don't believe there are any ADAS screens for the MK2, only plain versions and rain/light sensor versions (with and without top tint). ADAS systems tend to use a camera mounted in a triangle bracket and are a fair bit more advanced. The auto dimming mirror is self contained with nothing more than a power supply really. But since the bracket is different is does need the specific screen

Some other VAG cars can come with a dimming mirror but without the rain/light sensor


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## meteor (Nov 4, 2012)

MT-V6 is correct - the auto dimming mirror is self contained and does not need any special window glass. The dimming sensor is built into the mirrot itself next to the "Button A" (see SwissJetPilot's/workshop manual page in this thread) and is sensing the light coming from behind the car.

BTW - I s till have a spare Audi TT MK2 auto dimming rear view mirror 8J0 857 511 E with the plastic trim for sale - see my old posting in the TT-marketplace https://www.ttforum.co.uk/forum/viewtopic.php?f=15&t=1702305. The mirror become obsolete when I retrofitted the HBA functionality. Send me a PM if you are interested.

BR, meteor


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## 237tonybates (Jan 26, 2013)

IPG3.6 said:


> 237tonybates said:
> 
> 
> > Sont know this helps but ive done some mirror module transplants in the mqb mirror . Here's a photo of said area
> ...


Which style mirror do you have?

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## meteor (Nov 4, 2012)

" 237tonybates: Which style mirror do you have? "

Not sure whom you are asking (you are quoting on IPG3.6's posting) - the mirror I have for sale is for TT 8J, product number 8J0 857 511 E (interior mirror, anti-dazzle for vehicles with rain sensor, color 4PK/soull black) in mint condition.

Br, meteor


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## 237tonybates (Jan 26, 2013)

Someone asked me how to gain access into the mirror

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## meteor (Nov 4, 2012)

Ok - gotcha


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## spiette (Jun 1, 2013)

Please excuse this latest thread necromancy but did anyone make progress in finding the cause or disassembling the early auto-dimming/compass mirror?

My 2008 3.2 Roadster seems to have suffered from this. The green light won't turn on, the compass powers up briefly when you first turn the ignition on and will let you set the zone but then goes dark. The Auto mode on the headlights functions.

I haven't checked the fuses but the things that do work on the same circuits suggest they are ok.

I wouldn't be surprised if this was some leaking capacitor in the internal module but how to reach it...


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