# Retrofitting automatic headlights/wipers/anti-dazzle mirror



## MT-V6 (Jan 11, 2015)

Has anyone done it successfully?

As I understand, if you fit the mirror just power alone is enough for the auto anti-dazzle feature?

How about wiring the rest?

My windscreen has a crack so when I replace it I plan to get the correct one fitted.

From what I can see, either 8J0857511 or 8J0857511C is the mirror I need, obviously with some other parts


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## ReTTro fit (Nov 9, 2014)

You'll need :

Windscreen

Mirror (8J0857511)

Rain / light sensor

Light switch

Loom

Vcds

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## MT-V6 (Jan 11, 2015)

That's as I suspected rettro, do you know if there are any compatibility issues with this and a 2007 TT?

Have you managed it?

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## hot foot (Oct 7, 2016)

MT-V6 said:


> That's as I suspected rettro, do you know if there are any compatibility issues with this and a 2007 TT?
> 
> Have you managed it?
> 
> Sent from my Nexus 5 using Tapatalk


My 2007 has them all from the factory for what it's worth.


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## ReTTro fit (Nov 9, 2014)

I've done it one a facelift tt and a pre facelift A3 
Didn't have any issues

The Lin bus pin is on block F pin 3 on your cem

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## WoRkZ (Sep 19, 2015)

Stupid question but what is *Automatic headlights*? Do some TTs come with no Auto position on the lights button??? :?: We don't get TTs without this over here, that's why I'm asking. I never use that... I guess it automatically selects for you what lights are on (based on exterior light level maybe)? It would bug me to no end if the car didn't have only the lights I want on at a given time. Especially since I've retro-fitted my fog lights with HIDs. In the city, those are good enough for quite a while after the sun as set... and the car looks quite good with only the fog lights and LED accents on.


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## MT-V6 (Jan 11, 2015)

Thanks for confirming 'hot foot', and thanks rettro, I will have to ask you a few more wiring questions if that's OK?

Workz, it was an option in the UK, and only turns the headlights on it off, I think the driver has to do the fog lights. I had it on my previous corsa, and it's one thing I miss

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## WoRkZ (Sep 19, 2015)

MT-V6 said:


> Workz, it was an option in the UK, and only turns the headlights on it off, I think the driver has to do the fog lights. I had it on my previous corsa, and it's one thing I miss


Oh, so it's like the mandatory DRLs here then! Every car in North-America has to either have main headlights or dedicated DRLs on at all time on the road (mostly to prevent head-on collisions). On my Outlander, headlights come on when I start the car and on the TT, they come on when I release the handbrake. Thankfully, I can override this by manually selecting which lights are on... and I have the option of only the side markers and the fog lights.


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## ReTTro fit (Nov 9, 2014)

The handbrake function can be deactivated with vcds

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## MT-V6 (Jan 11, 2015)

ReTTro, could you advise me of what VCDS coding is required? I would like to have a look at the car and make sure the modules support:

Auto dimming mirror
Auto headlights
Auto wipers


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## ReTTro fit (Nov 9, 2014)

Rain & Light Sensor Coding

For coding just go to central electrics module and on the very first page of the long coding helper 
(byte 0) there is a bit that you need to tick saying 'rain/light sensor installed', tick that and your done.

Coming Home Lights Coding

Open 09 - Cent. Elect. and select Coding, then Long Coding Helper.
Check Byte 00 Bit 5 and Byte 00 Bit 7.
Close out and select Do It to write the changes.
Next under 09 - Cent. Elect. select Adaptation
Channel 01 is the number of seconds you want the coming home to be active - 0 to 120.
Channel 02 is the number of seconds you want the leaving home to be active - 0 to 120.

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## MT-V6 (Jan 11, 2015)

Cool, I definitely have that option available:









I have CH/LH lights enable already, in the same process as you say 

Does the auto dimming mirror require anything?


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## MT-V6 (Jan 11, 2015)

OK I've got a mirror on the way, for a bargain I think. Final fitting will have to wait until I get the windscreen replaced but plan to try and get the wiring and other parts sorted soon, for the auto-dimming at least.


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## ReTTro fit (Nov 9, 2014)

Whilst wiring you should both consider wiring to the door modules too and add dimming door mirrors 
The work from the centre mirror

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## MT-V6 (Jan 11, 2015)

Would that mean in future it is just a case of getting new door mirror glass? If so I will definitely do that too.

How would I code them?:


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## ReTTro fit (Nov 9, 2014)

Sorry I worded it wrong 
They only pass through the module 
The wires go from pins 4 & 5 of the rear view mirror to pins 1 & 10 of the 20 pin plug in the door loom then from there they pass through the module and out to the mirror glass itself where you'd also need to add the two wires

Yes once the looms I'm there and you add the new glass they dim along with the rear view mirror

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## hot foot (Oct 7, 2016)

Hi MT-V6 unfortunately I don't have access to PM's yet I was able to read it though and your assumptions were all correct.

This is a link with a picture from my car showing my lightswitch : https://www.dropbox.com/s/i6g0p5ahnhwt9 ... 8.jpg?dl=0


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## MT-V6 (Jan 11, 2015)

Thanks for that, now I just need to find it's part number!

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## ReTTro fit (Nov 9, 2014)

Do your homework mate 
There LOTS of switches and have minor pin differences 
There year specific

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## MT-V6 (Jan 11, 2015)

Yeah I've noticed! Any way to find out apart from ETKA and googling part numbers?

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## MT-V6 (Jan 11, 2015)

Ah, if I find a car on auto trader and give the reg to Audi, hopefully they will find it? The parts guy near me knows what i do and is very helpful. Or even 'hot foot' reg might be OK as same as as mine with same spec, eg no xenon or DRL,

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## ReTTro fit (Nov 9, 2014)

MT-V6 said:


> Thanks for that, now I just need to find it's part number!
> 
> Sent from my Nexus 5 using Tapatalk


8J2 941 531 L

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## MT-V6 (Jan 11, 2015)

ReTTro fit said:


> 8J2 941 531 L


Looks like the one  can't find any for sale currently so will see if any come up

Apparently about £65 from Audi

Also, a good informative thread here http://www.audi-sport.net/xf/threads/fa ... ed.143484/


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## ReTTro fit (Nov 9, 2014)

The 8P2 unit should be the same mate

https://www.ebay.co.uk/itm/222294315072

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## MT-V6 (Jan 11, 2015)

It doesn't have the aluminium though. In that link people have swapped the knob over, have you tried that?

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## ReTTro fit (Nov 9, 2014)

Yes I have mate 
I've got gloss black centre with ally sides in mine now 
Like this









The ally bit is a must, nice little touches that stand out 
I swapped my window switches too









If you want one with ally then you want "BJ"

https://www.ebay.co.uk/itm/122046294818

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## tttony (Dec 21, 2014)

Are the knobs permanently fixed to the light switches, or can they be removed and swapped over? Also the same question for the mirror switches.


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## MT-V6 (Jan 11, 2015)

Hi Rettro,

My mirror has arrived. In terms of wiring it has a 6 pin connector, I believe I need connector 8E0 971 833 for it:









Could you clarify where the 6 pins go (and maybe what they do for my reference?)

Pin 1 - 
Pin 2 -
Pin 3 -
Pin 4 - to pin 1 of the 20 pin plug in the door loom (for dimming wing mirrors)
Pin 5 - to pin 10 of the 20 pin plug in the door loom (for dimming wing mirrors)
Pin 6 -



ReTTro fit said:


> The Lin bus pin is on block F pin 3 on your cem





ReTTro fit said:


> They only pass through the module
> The wires go from pins 4 & 5 of the rear view mirror to pins 1 & 10 of the 20 pin plug in the door loom then from there they pass through the module and out to the mirror glass itself where you'd also need to add the two wires


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## ReTTro fit (Nov 9, 2014)

Mirror 
Pin 1 > Fuse 7 in fusebox.
Pin 2 > Earth
Pin 3 > Pin 1 12-pin connector, black (B) onboard power supply (underdash, drivers side)
Pin 4 > Pin 1 20-pin connector, black (A) Driver door control unit and passenger door control unit
Pin 5 > Pin 10 20-pin connector, black (A) Driver door control unit and passenger door control unit
Pin 6 > (Interior light)

Rain and light sensor 
Pin 1 > Fuse 16 in fusebox
Pin 2 > Earth
Pin 3 > Pin 3 8-pin connector, black (F) onboard power supply

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## MT-V6 (Jan 11, 2015)

ReTTro fit said:


> Mirror
> Pin 1 > Fuse 7 in fusebox.
> Pin 2 > Earth
> Pin 3 > Pin 1 12-pin connector, black (B) onboard power supply (underdash, drivers side)
> ...


Cheers, still piecing together info I will need 

Is the power supply near the CEM? I'm surprised the rain/light sensor doesn't connect to the CEM at all


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## ReTTro fit (Nov 9, 2014)

MT-V6 said:


> ReTTro fit said:
> 
> 
> > Mirror
> ...


The "onboard power supply" is wording for 
CEM mate 
"Central electrics module" supplies power to all the electronics 

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## MT-V6 (Jan 11, 2015)

Ah I didn't know that!

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## MT-V6 (Jan 11, 2015)

tttony said:


> Are the knobs permanently fixed to the light switches, or can they be removed and swapped over? Also the same question for the mirror switches.


Same as above really, think I've found a suitable A3 light switch but would want to swap my aluminium knob onto it


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## ReTTro fit (Nov 9, 2014)

Yes, just pull the knob off

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## MT-V6 (Jan 11, 2015)

ReTTro fit said:


> Mirror
> Pin 1 > Fuse 7 in fusebox.
> Pin 2 > Earth
> Pin 3 > Pin 1 12-pin connector, black (B) onboard power supply (underdash, drivers side)
> ...


Rettrofit, could you clarify pin 6 please? I understand this is to undim the mirror when the interior light is on as it says in the manual.


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## MT-V6 (Jan 11, 2015)

ReTTro fit said:


> Yes, just pull the knob off


I see, seems stiff so will try when off the car


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## ReTTro fit (Nov 9, 2014)

Pin 6 correct

Stiff knob ( she said not tonight) 

Yes there really tight mate but they do pull off

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## MT-V6 (Jan 11, 2015)

ReTTro fit said:


> Pin 6 correct
> 
> Stiff knob ( she said not tonight)
> 
> ...


Which pin of the interior light though?

Haha, was asking for that!


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## ReTTro fit (Nov 9, 2014)

Can't remember the pins on them mate 
Think there's only 5 in there, just put a multi meter on it and see what pin you get the voltage on when you turn the interior light on

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## MT-V6 (Jan 11, 2015)

Ah ok, so I'm not looking for a signal, just a positive feed?

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## MT-V6 (Jan 11, 2015)

I had it out before to add ambient lights

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## ReTTro fit (Nov 9, 2014)

No mate, only a pos feed when interior lights are switched on

It's so the mirror knows the interior lights are on and it's not a car behind you so it doesn't dim

I'm sure it's pin 1 mate but don't hold me too it 
Best to test, 2 min job mate

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## MT-V6 (Jan 11, 2015)

OK thanks, will try and check tomorrow. Almost have everything I need now to start

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## MT-V6 (Jan 11, 2015)

Finally got round to checking, but with no luck.

Interior light pin:
1 0v, earth
2 12v with door open, 0v the rest of the time (regardless of lights being on through the centre button, switching a reading light on makes no difference). Also seems to be earth?
3 0v, also no wire is in the loom to this pin
4 12v perm
5 12v with illumination/ambient lights
6 12v perm

I tried with ignition on and off. Am i doing something wrong?


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## ReTTro fit (Nov 9, 2014)

I wonder if anything alters once the cem is coded ?
I.e.: pin 3 becomes active

If not I assume it's pin 2

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## MT-V6 (Jan 11, 2015)

That's true, although I don't think the auto mirror has any coding changes?

I wondered about pin 2 but doors open wouldn't be that useful, I assumed it was if a reading light was turned on while driving, eg passenger using it, the mirror would undim

Waiting for wire to arrive anyway and the headlight switch is faulty so being returned, the illumination flickers


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## MT-V6 (Jan 11, 2015)

Finally got around to starting the wiring today. Made up the loom for the mirror and sensor and fed it up to the top of the windscreen from the drivers side footwell.



















I took out the courtesy light and the vanity light, as well as the A pillar trim so I could feed it through and cable tie it to the existing looms.



















Still need to connect it up.

I also starting wiring the coming/leaving home button to find that one of the pins is already taken, so that will have to wait until I can get the soldering iron outside.


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## MT-V6 (Jan 11, 2015)

ReTTro fit said:


> Mirror 
> Pin 1 > Fuse 4 in fusebox.
> Pin 2 > Earth
> Pin 3 > Pin B1 of cem
> ...


Annoyingly I can't continue for now, as I am waiting for a pin to arrive for C4.

Also CEM pins B1, F3 and K10 are already in use and so I need to splice into them.

However the cable is routed from the mirror to the footwell with the A pillar trim reattached, with the earth attached to the same bolt I used for the footwell lights, and ordered a couple of piggy back fuse holders as both are in use (my manual states fuse 7 for the mirror and 14 for the rain sensor), both 5A.


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## MT-V6 (Jan 11, 2015)

I have finishing wiring it all up. The mirror dims and undims, and undims when in reverse correctly, although it is disconnected for now until the new windscreen is fitted.

The rain sensor is connected and I think I have coded it correctly, as per below:
Byte 0, bit 7 (I unticked bit 5 and 7 which I had enabled in the past as I read it might interfere with the physical coming/leaving home button)









Byte 2, bit 4









I have added the extra light switch wire. The auto position is keeping the headlights on permanently for now.

The coming home/leaving home button indicator light doesn't light when pressed (button icon does illuminate).

I need to look into it more but is there anything to look for? Measuring blocks for light/rain etc?


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## MT-V6 (Jan 11, 2015)

Bump anyone?


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## ReTTro fit (Nov 9, 2014)

Surely the byte 0 bit 7 still needs to be active mate 
But I'd then dictated by the button

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## ReTTro fit (Nov 9, 2014)

Have you checked measuring blocks 16 etc ? 









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## MT-V6 (Jan 11, 2015)

Will take a look at that this evening. I'm sure the brightness was always reading 0.0 though

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## MT-V6 (Jan 11, 2015)

ReTTro fit said:


> Surely the byte 0 bit 7 still needs to be active mate
> But I'd then dictated by the button


Enabled this again so bit 5, 6 and 7 are enabled. The button seems to be working properly now. The DIS still shows the menu for coming home lights time only (can't remember if it showed leaving home before).

So the button all seems to be good



ReTTro fit said:


> Have you checked measuring blocks 16 etc ?


I had a look at the measuring blocks again, specifically group 8. The brightness does indeed change from 0.0-7.0 but since it was dark outside I used a torch on it. It only picked up any light if the torch was very close. I'm not sure if it detects sunlight differently so need to try that out. The headlights were on the whole time.

The rain quantity changes a bit but I haven't tried that yet. I have now taped the sensor to the screen so I can try pouring water over it.

I'm not sure what is meant to change in group 16 (brightness/lights on RLS). They both stay ON currently.


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## ReTTro fit (Nov 9, 2014)

Glad your sorted mate

Sensitivity of the light sensor can be adjusted mate

Ch / lh settings in DIS is a seperate code mate but can't remember which off the top of my head

Personally I'd prefer to control it in the dis rather than the button but you've got the switch with the button now

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## MT-V6 (Jan 11, 2015)

Yeah I saw the light sensor correction and rain sensor correction on the sensor coding, I left both on TT 8J for now

I quite like the button, is a bit easier to just press than in the DIS, but since it could be wired in I thought why not!

New windscreen is being fitted in a couple of weeks so I can tidy it all up (and get rid of this cracked one!)


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## MT-V6 (Jan 11, 2015)

How is the flat upper trim that the sensor wires clip into attached? I thought it would be sticky, but it just has felt on it. Does it just clip securely or something?

The lights definitely seem to work now, as do coming home /leaving home. I think the DIS functionality is dictated by byte 2 bit 4 - with it unticked you can use the DIS, else it is through the light sensor. The DIS still has time delay adjustment but not on/off as that is with the button.

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## MT-V6 (Jan 11, 2015)

New windscreen is now fitted and all parts and trim fitted and working 

Will write a guide for the KB at some point


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## technik21 (Mar 6, 2016)

Nice job.

I have this as a factory option, but I've noticed only the rear view mirror dims but not the side mirrors.
I thought all mirrors dim if you had this option ?


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## MT-V6 (Jan 11, 2015)

The side mirrors was an extra option I think. Can easily be done but the glass is £150 a side new so would have to find it secondhand to be worth it. I added in the wires for that so it is easier if I come across any

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## ReTTro fit (Nov 9, 2014)

I believe there dearer than that mate 
I've got a mint pair in my garage if anyone wants to make me an offer

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## MT-V6 (Jan 11, 2015)

Not right now but I'll bear it in mind Rettro  are you going to Stanford Hall on Sunday?

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## ReTTro fit (Nov 9, 2014)

I'm not sure mate, weather dependant, might pop up for a look around

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