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2005-Current Volkswagen Touareg, Audi, or Porsche Cayenne

Technical Bulletin
SUBJECT/Summary: Installing a brake control on a 2005-current Volkswagen Touareg or Porsche CayennePROBLEM: Difficulty installing a brake controller on a 2005-current Volkswagen Touareg or 2005-current Porsche CayenneSOLUTION: To install a brake control on a 2005-current Volkswagen Touareg, Audi, or Porsche Cayenne using the factory brake control connector, you will need to assemble a brake control harness from parts that you can obtain from a Volkswagen dealer. This harness will allow you to plug your brake controller into the factory brake control connector.
Select your vehicle to confirm the brake controller fit
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Assemble Harness
You will need the following parts (pictured above) that are available from a Volkswagen dealer - 1 connector housing (#1J0-972-782) and 2 wire/terminal assemblies (#000-979-228). Cut the wires from both wire assemblies in half so that you have 4 wires, each with a clip on one end and bare wire on the other. Connect the bare end of each of these wires to one of the wires on your brake controller, then slip the other end of each wire into its appropriate slot on the housing. The slots are numbered to make it easier to connect each wire correctly. The following table shows the correct wiring connections.
Wiring Connection Key
Volkswagen Part numbers 1J0-972-782 and 000-979-228
Connect to the Factory Brake Control ConnectorThe factory brake control connector is located under the vehicle's dash on the driver's side close to the door. You'll have to remove the appearance panel, which is held on by 2 Torx head screws. The factory brake control connector is underneath the panel and is wrapped in gray foam. Remove the foam and connect the housing to the connector.
Note: You may need to install a relay if you're using a Prodigy or P3 brake controller. The display of these controllers can be erratic when used on 2009-current Volkswagen Touregs and Porsche Cayennes. To avoid this problem, you should install a 12V, normally open relay. The following instructions and numbered diagram will help you install the relay correctly. (The Prodigy RF wireless brake controller uses radio signals to control the brakes on your trailer, so it does not need a relay.)1. Obtain locally, a 12 volt, normally open relay.2. Connect the ground terminal (85) of the relay to a ground under the dash.3. Connect the trigger terminal (86) of the relay to pin #3 of the brake control connector.4. Connect the red wire from the brake control to the load terminal (87) of the relay.5. Connect the source voltage terminal (30) to a 12 volt source. This wire should have a 5-amp fuse installed in-line.
Manufacturer: TekonshaBulletin Date: January 21, 2009Bulletin Number: TB0021

Terry P.


Hey there, recently installed a Curt Triflex controller on my VW TDI attached to the factory harness. As soon as the trailer is plugged into the vehicle, the Triflex begins clicking non-stop and the display flashes. Does this brake controller also need the relay installed? Called support at Curt -- they had me run a test via a test light that showed the brake controller is working fine without the trailer attached.....

David B.


Try hooking up to a different trailer and see what happens, if it works fine you have an issue in your trailers wire harness and need to start troubleshooting. If it happens again I would say you have a short between the red wire on the controller and the power wire. Worst case is you have a faulty unit.

Terry P.


@DavidB Thanks for the feedback. This one was a head scratcher for certain. I was finally able to find the issue and figured it is worth while putting it in the comments. This trailer has the trailer breakaway system including the breakaway switch, battery and charge regulator. I started disconnecting things to see if I could find the faulty component, and it turns out the charge regulator was the issue. Despite it being in a sealed container, it had become corroded and shorted out. Once it was removed, the brake controller operated normally. I have now ordered and installed a new breakaway system.

Ian M.


I am not quite confident with the additional relay when installing a RedArc tow pro elite since the keep alive voltage of the hot battery ensures that the calibration function remains in memory. Any removal of that keep alive voltage means that a recalibration is required after each engine shutdown. Based on that is it not counter productive to install a relay?

Les D.


The black wire at the controller is from a constant source and will ensure programming is maintained. The additional relay is connected to the brake pedal switch. You will need this relay for your system to function.

Ian M.





I see that this bulletin is for a Tekosha brand controller. The controller I'm looking at is a Redarc one. Is this wiring fix still needed? 2012 Touareg TDI with factory tow package. Thanks.

Victoria B.


Yes, you will still need additional components to install a Redarc controller in your 2012 Touareg. I have linked the page showing all of the brake controllers for your Touareg - which also shows an "Installation Notes" section to let you know which controllers require additional parts and which don't. That section will also let you know what the VW part numbers are.

Jeff K.


FWIW I called the manufacturer and as of 3/22/2021 this bulletin still applies, much to my chagrin.

Etrailer Expert

Kef G.


Thank you for the update!

Jeff K.


@KefG ...forgot to mention we have a 2017 Audi Q7.

Marc H.


The instructions about the relay are helpful, but: a. Where would I find/buy a 12V, normally open relay? Is there a part number to look for? b. How do I install a 5 amp fuse in-line? c. Where would I find/buy a 5 amp in-line fuse? s there a part number to look for? d. How/where do I find a 12V source to connect the relay to? e. Are there other connectors I'd need to install the 5 amp fuse or to connect to a 12V source? If so, what are those parts and where do I find/buy them? Thanks for the help and your patience.

Etrailer Expert

Jon G.


a. You would find a normally open relay at an auto parts store. b. To install an in-line fuse you would use something similar to part # SWC9545. It would just be in place of some of that 12 gauge wire. c. We have a mini fuse kit as part # PT62FR that you could pair with the part above to accomplish this. d. Usually a 12V power source that is hot all the time can be found with your cigarette plug or if you have an accessory outlet in your vehicle. Otherwise you'll just need to use a circuit tester to see which wire is hot all of the time. e. You'll need 12 Gauge Butt Connectors # DW05745-5 as well as a ring terminal, part # 44-5310A or # 44-5356A, to connect to your battery.



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