2008 Cayenne Brake Controller Install with Factory Wiring Harness

[seabass]

I just finished installing a Prodigy Brake Controller today on a 2008 Cayenne. I found a couple of write ups that were helpful but not completely clear.

First off if you have a Trailing Hitch installed on your Cayenne you also have a factory trailer wiring harness for a 7 pin connector. By the hitch, there is a blank plastic piece that needs to be removed and replaced with a 7 pin connector. You can get this connector from your Porsche Parts department, Part PNA-955-118-93,it was $30 CND so it will be like $2 in the US.

Now if you don't want a brake controller just buy a 7pin to 4 pin converter and you are done. Running lights, Brake Lights and Turn signals will all be working.

If you do want the brake controller, you need to build a harness. There is a pretty good write up from Tekonsha on how to make the harness for reference. http://www.macscheck...scheCayenne.pdf However what they do not mention is the newer Cayenne's do not have brake switch with a red/black wire, it has been moved into the engine bay. So you will have to make use of the brake signal in the factory 4 pin connector. Which in the end is just as simple, so lets start.

Parts.

Likely 10" of wire.

A bunch of squeeze on connectors if you can't soldier like me.

A 20A 12V micro breaker

A 20A/30A 12 4-5 pin relay, from an auto parts store (this will be labelled with pins 85,86,87,87a(not used) and 30.)

The VW connector, 1J0972782 and 2 VW connector wires 000979228

I believe all of these parts was about $70 with the connector wires being the most expensive.

The objective is to take the 4 pin factory connection under the dash and prep it for the Prodigy controller. For the most part this is direct connection.

1. Take the VW wires 000979228 and cut them in half so you end up with 4 wires with a connector on each end.

2. Insert all 4 of the wires into the VW connector 1J0972782. On the connector there are numbers 1 to 4.

3. Start with connector wire 1 which is the vehicle ground. You need to end up with two grounds, one for the prodigy harness (white) and one for the relay pin 85. To achieve the two wires, I used a marrette, twist the connector wire 1, the prodigy harness white, and 5 inches of other wire into one Marrette. Connect the new wire you added to pin 85 on the relay.

4. Take connector wire 2 which is the vehicle 12V, run it to the 20A 12V micro breaker, off the other side of the micro breaker use another Marette and bring in the 12V out of the micro breaker, the black wire from the Prodigy harness and 5 inches of other wire. Run the 5 inches of other wire to pin 30 on the relay.

5a. Take connector wire 3 which is the vehicle brake signal. Run is wire directly to pin 86 on the relay. What you are doing is converting the brake signal to a constant 12v signal that the Prodigy will understand.

5b. To finish up this, connect the red wire from the Prodigy harness to pin 87 on the relay.

6. Take connector wire 4 which is the vehicle output to the trailer electric brakes. Connect wire 4 directly with the blue wire on the Prodigy harness.

You should end up with something that looks like this.

A few shots of the parts:

The relay

The Micro Breaker

The VW connector

The Prodigy connector

The final CTT harness for any model year as far as I can tell.

So all you do is plug the harness in and connect the other end to the Prodigy. These pictures are were taken from some other peoples posts. Remove the lower plastic cover above the brake and gas pedal. One torx screw.

Look straight up on the left hand side and find the factory 4 pin trailer connector. It is inside a little grey cover exactly as shown below.

Plug the harness into the factory plug and test. Use a few zip ties to hold everything in place.

Test your harness without the Prodigy hooked up, you should have 12v between white and black on the harness. When you apply the brake you should have 12v between the while and red.

If everything checks out, put the plastic cover back on and mount your controller. The final test before hooking it up, is checking that pin 1 to 2 on the rear 7 pin connector gives you a voltage output when applying the brakes.

I hope that helps someone doing this simple install, the dealer quoted me $600 plus parts to do the same job, so I am happy with the result of doing it myself.

Happy towing.

[wvicary]

Result and excellent timing! I was just looking into doing this.

[stronbl]

Seabass - thanks for the great write-up and pictures. It was really helpful.

All - I have a 2013 Cayenne diesel with factory tow package. I just followed the above instructions and built a harness for my Prodigy P3 brake controller. After plugging in the controller to my new harness, I get 14v+ across the power when testing the P3 internal settings. But I don't get any voltage for the brakes or lights, according to the controller. These tests were done without a trailer hooked up so that may be the issue.

Just in case, am I missing something anyone may suggest checking? Do I need to have the Porsche dealer do anything to "recognize" the hitch and wiring, again it was a factory install item?

Thanks.

[jalexa27]

I am having the same brake light signal problem.  Any ideas on how to fix it?  The brake controller works well and as intended except for there is no brake signal coming from the vehicle.  I cannot find a signal from the factor harness when pressing the pedal.

 

Any help would be greatly appreciated!.

 

(I have a 2012 base cayenne with a manual transmission... )

[gchu]

After I did all the researches and finally ordered the Tekonsha Prodigy P3 trailer brake controller.

 

This information is from etrailer.com: confirmed with my contacts at Tekonsha, and Prodigy P2 # 90885 and P3 # 90195 have been re-engineered the to not require a relay for installing in a 2012 Volkswagen Touareg. The minimum voltage needed for the display on the brake controller has been increased, therefore the relay is not needed.

 

I connected the wire harness with the VW wires & adapter, straight with no relay, the controller seems to be working fine.  I don't have a trailer hookup to it yet, but I will post an update if there is any issue when that happens.

 

In additional, I found out the P3 doesn't go into sleep mode if a LED Trailer Light Adapter is being used for a trailer with LED tail lights.  Unplug the adapter the P3 goes into sleep mode in 15 minutes.

Edited August 29, 2014 by gchu

[gchu]

My trailer finally arrived.  I hooked up my trailer and everything seems to be fine.  No error or whatever showed up.

 

When I took the trailer for a test run and tried to adjusted the brake controller then I have some trouble.  By activate the manual override, I can't see to able to put the wheels to lock even set it at the highest power setting.  I did feel the brake worked and the trailer was slow down the vehicle, but the wheels didn't lock as a procedure to setup the power level.  The display at the controller was fine and no erratic display.

 

I may need to try the original method for this post by adding a relay and see what happens.  From the diagram of the technical bulletin, can someone tell me where can I get the source of the 12V that goes the relay?  Can I simply use the power source from the factory brake controller harness (red/yellow)?

 

 

[gchu]

I have some issues with my setup of the Tekonsha P3 controller without the relay but not sure the problem is the controller or not.  I am not sure the updated P3 still need the relay even the company said it is no longer necessary.

 

I want to try to add the relay to the harness and see if it is the cause of the issue.  For those who had successful installed, could someone tell me where you get the source of the 12V & Ground?  Can you use the 12V and Ground from the factory 4 pins and feed them to the relay?  Thanks.