So Easy A Porsche Dealer Could Do It: Cayenne Brake Controller Install

For a much more in depth write up, please see the tech article I wrote for our local Kansas City Region PCA. It can be found at and click on the newsletter archives and find the September-October 2012 issue, download it and go to page 6. Everything is explained in more detail.

A good buddy of mine brought over his 2011 Cayenne S for a trailer brake controller install the other day. The idea of a brake controller is to activate the electric trailer brakes when you hit the brakes. This helps to slow your speed smoother and quicker with a heavy load behind you. There is a lot of misinformation out there on this install, mostly dealing with the mystery factory wiring harness that the brake controller plugs into. For years, guys have sworn that the plug wasn’t there on their Touareg or Cayenne, but in reality, it has always been there, but the plug can be really hard to find under the dash. The install has changed slightly through the years, but overall is pretty straight forward.

We are using a Prodigy P3 brake controller which right now is considered one of the best controllers out there. I use one in my rig and it is a fantastic unit. At about $150, it is well worth the money.

As the sun goes down, we get to work 😉

The first thing to do was the install the factory 7 way plug at the trailer hitch. The wiring is there, just remove the dummy plug and plug in the 7 way receptacle.

Up above the brake pedal and to the driver outer side resides the FACTORY harness connector to install the brake controller. Using the male VW portion of the connector (gasp!), we splice in to the prodigy P3 brake controller harness and match up the wires as needed. Essentially we are putting a connector on the end of the Prodigy P3 brake controller wiring harness that plugs direclty into the FACTORY wiring under the dash. Since the new Cayennes and Touaregs no longer use a brake light switch on the pedal, you have to use a relay that feeds of the signal from the master cylinder sensor. It all comes through the FACTORY wiring harness, so no big deal. Power to power, ground to ground, trailer to trailer, brake signal to relay, power to relay, ground to relay and relay to brake signal on the controller. Pretty simple right 🙂

Here is the relay wired inline in the brake controller harness. After a little work, we had a fully functioning brake controller that is removable by simply unplugging the harness at the FACTORY connector under the dash 😉

2011 CayenneBrake Controller InstallP3PorscheProdigyRennsportKCRepairService

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February 22, 2013 at 5:54 PM

I am genuinely happy to read this webpage posts which consists of tons of helpful data, thanks for providing
such information.


    February 22, 2013 at 6:01 PM

    Thanks! We wish we had a great dealer in town like Champion that we could work closely with! Love watching all the new innovative products you guys put you!


February 25, 2013 at 10:14 PM

How do I get more detail about this section: brake signal to relay, power to relay, ground to relay and relay to brake signal on the controller.?

Lonny Reynolds

September 12, 2013 at 8:41 PM

I have a 2011 base Cayenne with a manual transmission. We ordered the car without a hitch. We later decided we would like a hitch installed and were told by our local dealer that the cost would be around $1200. Recently I found information about a Curt brand hitch made specifically for the 2011 and newer Cayenne for $142 from Auto Anything. I bought the hitch, and installation was very easy. My problem now is that I would like to get electrical installed for trailer lights. I went to the dealer we bought the car from and he said that they don’t like to install the trailer lighting and that it could be expensive. We went to another dealer that told us that they needed to hook the car up to their equipment to determine what would be necessary to do the job. After driving 60 miles and spending the time to have them hook the car up to their equipment, the only thing they could tell us is that they weren’t sure – but it could be as much as $2000 to do wiring for towing. They even said that it might be necessary to buy the Porsche hitch in order to get the wiring to work! I have read several posts from people installing aftermarket wiring kits on VW Touregs and pre 2011 Cayennes. Some sounded successful but others mentioned computer error messages after installation. Can you offer any direction regarding installation of trailer light wiring (will not need brake controller as the trailer is small) for our car? Getting frustrated.


    September 15, 2013 at 3:32 PM


    This should not be overly difficult, you will probably have to purchase a portion of the wiring harness which should connect in the rear of the vehicle somewhere to the main harness. From there the wiring likely needs to be activated through the dealer computer.

James Alexander

August 27, 2014 at 6:49 AM

Thank you posting the instructions!. I followed every step and so far the unit seems to be working as intended, except for one piece.

When I was checking the stock harness for the brake signal, I did not see any voltage from the brake light signal wire. When I push the pedal, there is no voltage going to the unit. My brake likes work.

Any ideas??


    August 27, 2014 at 5:32 PM

    Sounds like you might have a bad relay or switched connection at the relay.

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