Retrofitting Electric Tailgate - B8 A4 S4 RS4 DIY Guide

[***DK***]

I recently took on the challenge of retrofitting the electric tailgate motors to my B8 S4 Avant 2010.
I used quite a few already well written guides online to do this but thought I would bring them together into one doc and add my own version. I have referenced the other sources in there as well as I couldn't have done this without them.

 

[NHN]

Nice job.

 

[***DK***]

Should add the following points I forgot to mention.
The loom I got from AliExpress for some reason had 2 issues which needed correcting.
1) the tailgate button would not light up when the car side/headlights were on.

2) the tailgate would not open/close with the ignition on.

To correct 1. I cut the white wire at the tailgate button plug and wired a new wire from the plug to the boot lights white wire on the side wall of the boot. They come on when you open the boot so then power the button light as well.

To correct 2. I think there was a grounding issue as there seemed to be 12v running down the 3 brown wires to the tailgate button.

I cut all three brown wires at the plug, joined them together and ran a new ground wire to the grounding point in the side compartment.

After that everything was fine.

I think there is a spare 2 pin plug on the loom that is supposed to go to the parking sensor buzzer but is not needed for the tailgate retrofit. I think maybe is for the towbar retrofit which this loom claims to do both from it's title.

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[***DK***]

Run into a problem.. tailgate wouldn't open today. Open circuit fault motor 2. I can only lift it a little bit as it has so much resistance I'm scared to go up any more manually. What do people do when you have a flat battery and need to get these electric tailgates up?

I took off the top trim cover from inside and noticed straight away that there was water in there clearly dripping on the motors/modules.

I've dried them both with a drier but still no good. Hoping it might come to life tomorrow but doubt it. Perhaps a new motor may be needed. Very annoyed

Not quite sure where this water has come from but the car has been sat with a cover on since November so perhaps condensation formed or maybe sunroof drains blocked and water from washing.

This is going to be difficult to replace if I can't open the tailgate.

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[***DK***]

All sorted again now. It was the right side motor/module that has failed. Probably from water damage but not certain.

Refitting again and I saw something I missed on the first time around. Not sure how as it's pretty obvious.
On the motor arm there should be a bolt rod (circled yellow) that then goes into a hole in the top corner of the boot behind the hinge area. That holds the motor steady while it's lifting up the tailgate. My first set didn't come with those bolts so if buying on ebay either look for a set with them on or you'll need to put a bolt and nut set on.

Also another thing. Make sure the set comes with the black bracket on the motor arm. Some seem to take this off. (Red circle). My latest one came with it but it was in pieces. Once assembled I had to put through the motor arm and secure the end with a star shape retaining clip. Push hard onto the end of the rod and eventually you hear it clip into place. Since the star retainer has a circular opening and the rod is rectangular it's quite difficult to push that retainer on.

I'll look to update the guide document when I get a sec.

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[litlol]

Did the lift motors have component protection? I bought an avant, realized the lift did not work. Opened it up to see the left motor was missing. I ordered one off eBay but when plugged in gives EEPROM error with obdeleven. Have not checked with vcds yet if that gives more info. It may be wrong part number as original was not there to take number from and I'm sure I did not do enough research but would you know if it is locked or did I just get the wrong part? 09 B8 avant btw.

 

[***DK***]

There is no component protection on lift motors. Left side (passenger) for UK should be 8K9 827 851.

These end up plugging in to the BCM2 comfort control module (J383) which could have an eeprom issue if perhaps had been taken from another car as a second hand part in the past. I would expect though you'd have lots of other electrical issues if that was the case though as it controls many electrical elements in the car. Hopefully just a bad part on the lift motor. Post back when you fix it?


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[litlol]

There is no component protection on lift motors. Left side (passenger) for UK should be 8K9 827 851.

These end up plugging in to the BCM2 comfort control module (J383) which could have an eeprom issue if perhaps had been taken from another car as a second hand part in the past. I would expect though you'd have lots of other electrical issues if that was the case though as it controls many electrical elements in the car. Hopefully just a bad part on the lift motor. Post back when you fix it?


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Thanks for the response! The one I have is 8K9827851
There seems to be an 8K9827851A version also.

Just to check, is it possible that the left motor is a slave to the right and need to be replaced in matching pairs? I believe repair manual said they do need to be replaced in pairs but did not say why. Have you used unpaired parts?

 

[***DK***]

I got my motors separately and then one died within a few weeks so I replaced one again.

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