Retrofit: Auto-dimming rear view mirror & CH/LH (picture heavy)

maccalo

Norway
Writeup for retrofitting auto-dimming rear view mirror and coming home/leaving home function to any A4 B6 with highline equipment.

This retrofit requires some knowledge of car electrics, and a registered version of VCDS lite.

How do I know if my car is highline?
If you have bulb out warning - you have highline
If your CECM part# is 8E0 907 279 E or F - you have highline

NB! You need CECM 8E0 907 279 F, which is the only CECM supporting AUTO lights and CH/LH function.

I did not do the auto dimming wing mirrors, hence it's not a part of this DIY.

Disclaimer: I am not a mechanic, and will not take responsibility for anything that may be damaged or broken while using this DIY on your own vehicle. This DIY is intended as a guide only.

Prerequisites

Parts
  • CECM (Central electrics control module) - paid $37
    8E0 907 279 F (always installed in S4)
  • Auto-dimming rear view mirror w/ light sensor - paid $50
    8E0 857 511 (Gentex 015621)
  • Headlight switch w/ AUTO position - paid $16
    8E0 941 531 B
  • CH/LH switch - paid $25
    8E1 919 094 B (LHD, for cars with xenon)
parts.jpg


Wiring
  • Plug for CH/LH switch (8 pin) - paid $10
    8Z0 972 883
  • Plug for auto-dimming mirror (6 pin) - paid $10
    4B0 971 833
  • Wires 20-22 AWG, 3 metres - paid $15
    White, black, grey, green
  • Cloth tape for OEM appearance - paid $3
    For OEM appearance of harness
  • Audi repair pins - paid $10 for 10 pcs
    000 979 018 E
wiring.jpg


DSC_0603.jpg


Let's get started

DISCONNECT YOUR NEGATIVE BATTERY TERMINAL.

DSC_0605.jpg

Remove interior dome light cover (just pulls out)

DSC_0607.jpg

The second plastic cover also just pulls out (has 4 plastic clips on it)

DSC_0608.jpg

Remove two philips screws to remove the base of the panel

DSC_0609.jpg

Then you can pull the base downwards to remove it

DSC_0610.jpg

Locate this plug, and remove it (two wires to be inserted here later)

DSC_0635.jpg

Remove the sun blind on the drivers side, by pulling out this cover and unscrew the T25 bolt behind it

DSC_0701.jpg

You also need to remove this handle to loosen the A-pillar trim (Torx 25)

DSC_0696.jpg

Loosen the A-pillar trim by unclipping the 3 clips along the A-pillar (note: my new wiring is shown here, not yet zip tied)

DSC_0616.jpg

Pull out your old headlight switch by pushing, turning clockwise and then pulling outwards.

DSC_0617.jpg

Remove the plug. Note: this is also a way to check if your car is highline - high gauge wires indicating highline, low gauge (thick wires) indicating lowline (lights are then operated by switch, not CECM).

DSC_0618.jpg

This cover pulls straight out

DSC_0620.jpg

Remove drivers kick panel - 3x 8mm hex bolts, first one located as shown on picture, last 2 located above the pedals (one on each side)

DSC_0625.jpg

Unscrew and unclip the fuse panel and pull it downwards to expose the CECM.

DSC_0629.jpg

Unclip all 3 plugs on the CECM and locate the 32-pin grey connector - it should look like this

DSC_0634.jpg

Remove the purple lock, and pull out the white center frame
 

maccalo

Norway
The fun part: Wiring

I've been searching the web, and found several good writeups, both in English and German. Based on the information I found, I have made a new wiring diagram in English, with all the correct part numbers and pin outs:
wiring-diagram-chlh-auto.jpg

Feel free to use this!

DSC_0643.jpg

Wire harness in the making

DSC_0647.jpg

Finished harness. It measures approx 2,5 metres from mirror end to CECM end. I used the cloth tape as pictured above to make it look OEM.

DSC_0652.jpg

This pictures shows the mirror connector and the loop that goes via the interior dome light connector.

DSC_0640.jpg

Remove the platic cover from the 12-pin dome light connector, by unclipping it from the right end of the connector as it's shown in this picture.

DSC_0642.jpg

This connector already had two unused pins! Insert your wire from pin #6 on the mirror end, in pin #1 on the plug. In pin #11, insert the wire running to pin #19 on the CECM.

DSC_0699.jpg

Zip tie the wiring harness along the existing wires in the A-pillar, and make sure it doesn't get in the way of your airbag.

DSC_0655.jpg

3 pins to be inserted into the headlight switch connector. The 2 blue wires inserts into pin #7 and #16 (these are also open). The black wire should replace the wire in pin #1 (remember: this black wire is connected with pin #1 on the mirror, pin #4 and #8 on the CH/LH switch and runs to pin #18 on the CECM). Make sure to insulate the old wire from pin #1 and tuck it away.

DSC_0658.jpg

Insert the 5 pins into the 32-pin connector on the CECM. All these slots are open, which means no tapping into wires!

DSC_0659.jpg

Connect your ground wires to the grounding point behind the instrument cluster. If you copy my harness design, you should have plenty of length to reach this spot.

Installing the mirror

DSC_0704.jpg

The old mirror pops off with a slight pull against you from one side. When it does, the base is still attached to the windshield. To remove this, get a firm grip around it and twist counter clockwise. No tools needed in my case!

DSC_0706.jpg

This is how the B6 mirror base looks like when removed. I forgot to take pictures of the windshield base whilist installing the new mirror!

DSC_0692.jpg

Place your new mirror against the windshield base with the wiring extension end pointing in a 10 o'clock direction. Push slightly against the windshield, so that the hooks are engaging, and turn clockwise until it clicks in place. Connect the harness and install the wiring cover trim.

DSC_0702.jpg

How it looks like from the outside

VCDS coding

vcds-1.jpg

Enter 09-Cent. Elect. to recode the CECM module

vcds-2.jpg

Follow the instructions given in this picture.

By now, your car should have a working auto-dimming rear view mirror, coming home/leaving home lights activated at dusk/night time, and auto lights if you're coded for the proper region.

My total cost for this project was approx $175 (excl. shipping).

Thanks for looking :sm4:
 

maccalo

Norway
Thanks.
Just had a chance to play with it. Here is how coming home / leaving home feature works (for those who don't happen to know):

- In dusk/night time, front fogs, tail lights and number plate lights will light up when you unlock the car (leaving home). When you switch off your ignition, and open the drivers door, the same lights will come on (coming home) for 30 seconds.

In VCDS, you can use adaption channel 01 on 09-Centr. Elect. module to change the "coming home time" (1-60 seconds).
 
Last edited:

spooka43.0v6

Registered User
Hello old post but hopefully still alive.
I also did the upgrade to auto light and ch/lh function. But keep having some problems. In my car there was already a dimming mirror but without lightsensor. So i changed the mirror for one with a sensor. And it works (dimming at dark) and also upgraded the cecm to f index. But still the lights switch on (in auto position) when it's not dark.. The ch/lh works when open or close the car. I have a wire connection from the white wire from the mirror (black/blue one in the cars wiring) and now i also get the warning light from the head light adjustment. Can some give me some advice...... thanks
 

neil ratcliffe

coupe rebuild master
did mine a few weeks ago a must have mod. this is the pics from mine.
 

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Visa_broke

Registered User
nice writeup and something i've been thinking about doing, (mine has the auto dimming mirror with compass so think thats slightly different) just missing the ch/lh stuff. Just not sure if i'd be up to doing the wiring
 

007BJF

Registered User
Hello, is there anyone wich can advise me? I've got B7 and I bought mirror Gentex 8H0 857 511 6PS( with compass-i suppose ), CECM 8E0 907 279 F, and switch coming home and switch headlight with auto- they are coming soon. I've got on my car central module 8E0 907 279 N and first of all, I wanted to change the new central module F, but there is a problem when I turned on my car my wipers are stuck in position ON, the washer pump not working, the light parking ON, and fog lights doesn't work as well. So literally the new central module F doesn't work on my car! I've got VCDS, just I need some help how can I have central module F adapted in my car. King regards
 

Mr_Dude

Registered User
The fun part: Wiring

I've been searching the web, and found several good writeups, both in English and German. Based on the information I found, I have made a new wiring diagram in English, with all the correct part numbers and pin outs:
wiring-diagram-chlh-auto.jpg

Feel free to use this!

DSC_0643.jpg

Wire harness in the making

DSC_0647.jpg

Finished harness. It measures approx 2,5 metres from mirror end to CECM end. I used the cloth tape as pictured above to make it look OEM.

DSC_0652.jpg

This pictures shows the mirror connector and the loop that goes via the interior dome light connector.

DSC_0640.jpg

Remove the platic cover from the 12-pin dome light connector, by unclipping it from the right end of the connector as it's shown in this picture.

DSC_0642.jpg

This connector already had two unused pins! Insert your wire from pin #6 on the mirror end, in pin #1 on the plug. In pin #11, insert the wire running to pin #19 on the CECM.

DSC_0699.jpg

Zip tie the wiring harness along the existing wires in the A-pillar, and make sure it doesn't get in the way of your airbag.

DSC_0655.jpg

3 pins to be inserted into the headlight switch connector. The 2 blue wires inserts into pin #7 and #16 (these are also open). The black wire should replace the wire in pin #1 (remember: this black wire is connected with pin #1 on the mirror, pin #4 and #8 on the CH/LH switch and runs to pin #18 on the CECM). Make sure to insulate the old wire from pin #1 and tuck it away.

DSC_0658.jpg

Insert the 5 pins into the 32-pin connector on the CECM. All these slots are open, which means no tapping into wires!

DSC_0659.jpg

Connect your ground wires to the grounding point behind the instrument cluster. If you copy my harness design, you should have plenty of length to reach this spot.

Installing the mirror

DSC_0704.jpg

The old mirror pops off with a slight pull against you from one side. When it does, the base is still attached to the windshield. To remove this, get a firm grip around it and twist counter clockwise. No tools needed in my case!

DSC_0706.jpg

This is how the B6 mirror base looks like when removed. I forgot to take pictures of the windshield base whilist installing the new mirror!

DSC_0692.jpg

Place your new mirror against the windshield base with the wiring extension end pointing in a 10 o'clock direction. Push slightly against the windshield, so that the hooks are engaging, and turn clockwise until it clicks in place. Connect the harness and install the wiring cover trim.

DSC_0702.jpg

How it looks like from the outside

VCDS coding

vcds-1.jpg

Enter 09-Cent. Elect. to recode the CECM module

vcds-2.jpg

Follow the instructions given in this picture.

By now, your car should have a working auto-dimming rear view mirror, coming home/leaving home lights activated at dusk/night time, and auto lights if you're coded for the proper region.

My total cost for this project was approx $175 (excl. shipping).

Thanks for looking :sm4:

Hi,

a doubt, your rearview mirror, in the area of the light sensor, is right against the glass?

my mirror has a little slack, is that why I always have the lights on?

11c4c26ed49dea41ffd9865a563b233f.heic


Thank you so much


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007BJF

Registered User
Hi, indeed it is similar to your mirror. I did it, the diagram wiring but I don't have yet switch CH/LH and headlight auto.Anyway the new central module F, it doesn't seem to be working.
 

Mr_Dude

Registered User
in my own, I have already changed to module F and I have put all the necessary material for the auto and FL lights to work, however, having the button in the Auto position, the same day lights are always on


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007BJF

Registered User
Alright, but have you got any problems similar to me? regarding the wipers on and light parking..... do you own a B7?
 

Mr_Dude

Registered User
I have a B6, my only problem is just to always have the lights on, even during the day, when they should only call at night, or go through a tunnel for example


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007BJF

Registered User
I suppose it is annoyed to have the light on anytime, do you remember if all 5 slots who needs to be inserted into the central module where free ( no wire)? I've got pins 18 and 19 with wire. My car is made in 11/2007.
 

maccalo

Norway
Florin: The 8E0 907 279 F module is only for the B6. The B7 uses a different CECM, hence why it is not working on your B7. I am not confident which part numbers would be applicable for this retrofit in the B7, but I'm sure the info is out there.

Mr_Dude: I suppose you can use measuring blocks to figure out whether the light sensor is working correctly or not.
 

Mr_Dude

Registered User
Mr_Dude: I suppose you can use measuring blocks to figure out whether the light sensor is working correctly or not.[/QUOTE]

Thank you, Maccalo, you know the channel to confirm it? is there any specific configuration? Thanks




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maccalo

Norway
I just sold my B6 this weekend, so I am not able to confirm unfortunately.
 

Stu.Audi

Registered User
I got this full roof loom inc dim mirror plug run all from down the passenger side plug
I got the dim mirror
Question is
Will it work and power up ?
67b60ba7e25acc877448fe9a50c2702f.jpg
0b7640a8adb43eb8aa124230fe7ddef2.jpg


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RS4dal

Registered User
I got this full roof loom inc dim mirror plug run all from down the passenger side plug
I got the dim mirror
Question is
Will it work and power up ?
67b60ba7e25acc877448fe9a50c2702f.jpg
0b7640a8adb43eb8aa124230fe7ddef2.jpg


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Is that loom from a B6 or B7 ? If B7 where does those orange and purple plugs fit ?
 

Stu.Audi

Registered User
Is that loom from a B6 or B7 ? If B7 where does those orange and purple plugs fit ?
Purple plug is not need as it is for Bluetooth mic also rain sensor and auto light
It off b7 model and mine is b7
The orange plug is in the front passenger side kick panel

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RS4dal

Registered User
Thanks .
Would you be able to do me a favour please ? Would you take a close up picture of the orange and purple plugs so I can see the wiring colours as this is what is confusing me on my autolight/ mirror install on my b7 .
 

Stu.Audi

Registered User
Sorry never saw this
It all in the car orange is plug in and not the purple as don't need it
So I got the interior lamps working and sunvisor too but the dimmer is not
5e8fc665702c5eebbf63aaa18bd98726.jpg
7aec22a9d6a242e6ebaa8a2f15e71b87.jpg
697c5e045719b1fe2354862e867a30c2.jpg


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Nightingale

Registered User
Can you wire/code Coming home feature so that Xenon or DRL lights turn on instead of (or along with) the fog lights?
 

Karlos the Avant

Registered User
I recently purchased some of the parts to carry out these mods on my 2005 S4 cab but then I found the wiring is different in the cab, my cab interior light only has 6 wires on the connecting plug so not sure what wires go where on the cab :readit: :wtf::sos::sos::sos::sos::sos:
 

neil ratcliffe

coupe rebuild master
yes the mai wring harness for a non diming mirrior is diffrent to a model with auto diming mirrior you will have to modifie your cars loom.
 

danijeel3

Registered User
Hello Team,

I need your help regarding the Audi a4b6.
The thing is that I have the original auto-dimming rear-view mirror and when replacing the exterior glass I noticed that I have an excess cable which is for external auto-dimming.

I found the exterior glass with that function, but it does not work. So, the auto-dim function works only for interior glass.

Can you tell me if this is only coding related issue? If not, please advise me on what should I do.

Thank you in advance.

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