Genuine Audi Swivel/Retracting Towbar Retrofit for A4 B9 and Allroad

[AudiFan2021]

For anyone seeking to install an authentic retractable towbar, here are the instructions. If your objective is just to execute code for a detachable towbar (utilizing authentic Audi components to interface with the CAN bus), you may adhere to the following subset of instructions.

Prerequisites - Audi A4 B9 (Allroad) - these vehicles are equipped with tow preparation; nevertheless, I have been unable to get a clear explanation from Audi on its specifics.

- Audi A4 B9 - verify that there is enough room in the well behind the rear bumper for the towbar to be installed and extended. The cutout is around 30 cm in width and 20 cm in depth; I suspect that for A4 vehicles, it may need modifying the area at the bottom of the rear bumper. The placement of the aperture ensures that neither the opening nor the towbar is visible when retracted.
- VCDS or VCP - for the installation of a detachable towbar, coding may be accomplished only using VCDS. If you are adding a retractable towbar, you may code it using VCDS, provided that your tow controller has been parameterized. If not, you must VCP to enable parameterization. This procedure takes 30 seconds and is a facilitated feature inside VCP, hence I am willing to assist anybody in need.

Components - Authentic retractable towbar

Allroad 8W0800491N - B9 The last character of the aforementioned part number varies according to the model; you may ascertain the appropriate fit for your vehicle from Audi.
- Wiring harness, switch, and controller: https://wibutec-shop.com/Kabelsatz-fuer ... Audi-A4-8W

- Tow Controller (I acquired mine directly from Audi, purchasing just the wire loom from Wibutech) 4M0907383F (notably, the last number seems to vary across various models.)
- Tow bar release switch 8W0951511 (acquired directly from Audi)



- OR detachable towbar https://wibutec-shop.com/Westfalia-Anha ... Audi-A4-B9 - Wiring harness and controller - 7 or 13 pin connection https://www.pfjones.co.uk/audi-a4-b...d ... g-kit.html

Implementation
The instructions from Wibutech are available in a 10Mb PDF, which I cannot upload here but may provide to anybody who want them.


Programming
The Wibutech paper includes the necessary coding instructions, which are as follows:

09 - central electrics (security code 31347)
Extended coding: hitch_ecu - modify to installation

46 - Central Module Comfort System Trailer Monitoring – Change to Active Trailer Control Unit – Change to Installed

3C - Lane Change Assist ECU for drawbar – modify to include ECU for drawbar Or Trailer control unit – modify to indicate installation

17 - Dashboard Trailer – modify to affirmative

6C - Reverse camera system equipment AHK/trailer detection – update to installed

74 - Chassis Control System Trailer – Modify to Installed

10 or 76 - PDC controller Trailer – modify to allow manual removal of the trailer device

13 - controller distance regulation (security code 20103)
Control module for towing sensor/Control module for trailer – update to installed

A5 - front sensor driver assistance system AAG/Trailer electrics – modify to coded

6D - boot lid electrical control unit
Alter trailer/controller for trailer to installed



Parameterizing the Control Unit
I had a problem here; I had completed all the preceding steps, however the release button for my tow bar remained inoperative. I attempted to modify the coding choices in VCDS, but it resulted in no discernible change. If fortunate, your control unit may already be parameterized; otherwise, you will need VCP to do this. A screenshot is shown below; using the VCP file manager, download the ZDC file for the Audi A4 Tow Controller and thereafter use the File Upload option to transfer it to Module 69. The whole procedure took under 30 seconds after I understood the necessary steps, and the button functioned instantaneously.

[David_Smith2003]

I want to install a retrofit genuine retractable towbar.

I visited Audi to purchase the component. The provided number is 8W0092157B, however I was informed that it requires license activation to function. The reseller refuses to activate it if I do the installation independently.

I have not purchased it yet; I am inquiring if it is feasible to activate the control unit using VCP.

[AudiFan2021]

Excellent inquiry. I recommend consulting an independent towbar installer about its activation.

[almamater78]

Do you own a PDF of the wire installation? I am intending to create my own harness. I have identified the necessary connectors; however, I am uncertain about several connecting locations in the Audi wiring.

[AudiFan2021]

I regret to say that I do not.

[KARlosfuentes]

I have the same issue with the button.

Do you own the ZDC file?

[AudiFan2021]

I regret to inform you that I do not.