Just wrapped up install of an OEM hitch, wiring, control module on my 08'.

The lights are working and turn signals function ok but brake lights are not working! Also, the lights stay on the trailer when I turn off the lights on the cayenne. Only way to get them to turn off is remove the umbilical cord from Cayenne. I do have led tail lights on my Airstream.

I checked fuses and noticed all of the fuses are already installed in the fuse box that have to do with the trailer hitch. At this point I am assuming something needs to be activated via programming? Anyone have experience with this? If this is the case can I use a Durametric cable or does it need to be a PIWIS?

And what exactly does the tow module do? Is it really needed or should I just tap into the brake lights of the Cayenne? Seems to be the simple solution.

 

I'm just getting into mine ('16 S), so I don't have compete information yet. I've installed my hitch and control unit so far this week. I understand that the car needs to know there is a hitch installed (PIWIS). Also, I've learned that the latest controllers have been updated to detect the LED lights on your AS. Apparently there is an aftermarket adapter pigtail available for earlier cars to detect LED lights. Go to the Suncoast website to find it.
Factory information is non-existent for you and I, I'm afraid. It would be nice if the factory 'brake controller' actually engaged and manged the trailer brakes somehow. I think it only sets up the car programming and enables the power to the 7-pin plug. I'm thinking I will use a wireless brake controller to manage trailer braking.
Good luck! I hope to join you soon... Our 25FB will come off the line mid Sept.
Kirk
PS: There is a Cayenne, Touareg, Q7 group on the AS Community site with a lot of information. http://www.airforums.com/

 

The early Cayennes (and Tuaregs and ML's and X5's and Q5's) have Bosch electronics that are not LED aware. The system assumes incandescent lights and monitors the current. If it is low, as it is with LEDs, the system thinks the lights are out and freaks.

There's a $20 dongle that solves the problem. How do I know? I've just retired and have spent the last year exploring NA with our Airstream See the airforum thread mentioned above.

Here's the part that plays well with our 2006 CS.

 

Update: I took the car to the Barrier Porsche in Bellevue to have them activate the tow module. After an hour later the tech comes out to tell me that he can't figure out how to activate it and he will need it for a full day to go over the entire wiring. He questions my install and says there is wires with butt connectors in the area. I ask him to show me what he means and he points out my aftermarket speaker wiring and crossovers 🙄 Scary to think this kid is a Porsche tech! I think I will try another dealership and ask for a senior tech this time. Frustrating....