Tekonsha P3 brake controller on the Touareg

This post isn't really about Bumblestook but rather her support vehicle, The Egg (Touareg). When I first got the Touareg for towing, I opted to go with the Tekonsha Prodigy RF. It's a wireless brake controller where the brake controller electronics sit in a weather proof box on the trailer itself and you have a wireless controller to set the power. I chose it because it's super convenient and you don't have to mess with the VW electrics but it has a few limitations:

1. Since the brake controller is on the trailer, I can't actually tow a different trailer if I ever had to since the Touareg effectively doesn't have one installed on it
2. If you use the hazards, it actually disconnects power to the brake controller as it flashes 
3. It takes up space on the trailer tongue that could instead be used to bring another spare tire! (This is the main reason motivating me to make the switch.)

To address this, I decided to switch to the Tekonsha Prodigy P3 which hardwires into the brake controller wiring already present in the Touareg if you have the factory tow package installed. Why didn't I do this the first time? Well for starters, the Touareg was new and I didn't want to drill anything. I also was weary of the difficulty as many DIY threads on this on clubtouareg.com indicated that the plug would be all the way up in the console and difficult to get to. However, now that the Touareg is a bit older and I have fewer reservations about popping open panels, I figured I'd give it a try.

Important VW wiring to make a wiring harness

To make things easier, rather than splicing the P3 into the factory wiring, it's recommended to instead use some readily available wiring parts from VW to fabricate your own wiring harness. I ordered these from ECS Tuning. You need one 4-pin connector housing (manufacturer part number: 1J0972782, ECS part number: ES311294) and two wires with flat connectors and retaining lugs (manufacturer part number 000979228E, ECS Part number: ES1009146). You cut these two wires in half and you end up with 4 identical length "half-wires" with flat connectors on one end. These four wires go into the four slots in the 4-pin connector housing. I then soldered the other end of these wires to the wiring harness included with the P3 using the following pin diagram and sealed everything with heat shrink tubing.

PIN1 - White - Ground
PIN2 - Black - 12V
PIN3 - Red - Brake lamp signal
PIN4 - Blue - Trailer brake output

This pin mapping is found in Tekonsha's bulletin on on wiring up their controller for a VW Touaregs and Porsche Cayennes which is available as a PDF online. In that manual it says Pin3 should be connected to a relay but it's been determined by the guys on clubtouareg that for T3 Touaregs (post 2012?), you do not need the relay. 

Touareg to P3 wiring harness done - 10/3/2015

The next part I thought would be the hardest...trying to locate and fish out the OEM brake controller connector under the dash. I was expecting the worst and for it to be all the way up in the A-pillar but instead I got a nice surprise, it was dangling right behind the panel where the ODB2 connector sits. As soon as I pulled the panel (held by two Torx20 screws), I looked up and there was the connector hidden in the foam wrap that I then cut to expose to OEM plug.

The foam behind the purple ODB2 connector hides the plug

Cutting open the foam reveals the 4-pin female connector

The next part was super simple. I just plugged in the male connector from the Touareg to P3 wiring harness I made and mount the bracket for the brake controller under the dash just past my left knee angled up so I can the display and operate it easily.  I put the panel back and routed the wiring as much as I could behind the dash and then plugged the wiring harness into the back of the P3. I'll probably clean this up with a wire loom later but for now it works quite well.

Tekonsha P3 installed - 10/3/2015

 

P3 operational - 10/3/2015

Trailer hooked up and operational - 10/3/2015

Big thanks to Steve at SJF Performance for letting me use his shop to work from and letting me borrow some tools to make the install a bit easier.