Part 2 of 2
I then used an adapter to convert the 7 blade Pollack RV connection to a 4 pin trailer connection. There I plugged in a Harbor Freight LED trailer light to test the function of the system. To my dismay the lights flickered and flashed randomly, indicating an obvious problem. Applying the brakes, and turn signals made no difference. At this point I had that sinking feeling.
Fortunately, further research revealed that Cayenne (and other European vehicles) were not compatible with LED trailer lights. Apparently the problem lies in the fact that the LEDs draw so little energy and fools the system that there is a problem. The solution is using an adapter that adds resistance to the system to fool the tow module controller that you are using incandescent lights rather than the LED trailer lights.
I then hooked up a set of incandescent lights to my Pollack connector and the system worked as designed!!
At this point all that was left to do was remove panels and properly install the hardware. Refer to the AFTERSALES installation guide for diagrams and illustrations of what I am about to describe.
Once you remove the EZ access panel for the CD changer, you will notice an oval hole underneath the area of the right side tail light. This hole is at the rear most portion of this access area on the same plane as the bumper. In this oval hole is a cream colored foam insert, carefully remove this foam. Once removed you should see a rubber plug. Your wiring harness will have a replacement plug which allows the wires of the harness to pass through (refer to the photo). Once this original rubber plug is removed, go underneath the corner of the car on the right (passenger) side and feed the pigtail that connects to the control unit through the hole. You may need to rotate/twist/turn the pigtail to fit through the hole. Then feed the harness through and also pass the green pigtail through the hole.
Once this is done go back inside the car and pull the harness about ½ way through. For the time being, tuck it in the CD recess while you tackle the biggest pain of the entire project.
Removing the right rear panels. My best advice is be patient. Read Wayne’s write up on how to replace the rear hatch struts. Consider a complimentary gain by replacing the rear hatch struts with QUALITY replacements while the panels are removed. This is a job you want to do as infrequently as possible. Follow Wayne’s directions, the photos really helped me understand what I was doing. One good thing about this part is that once you remove the rear headliner panel, the D pillar, the C pillar, and the rectangular tie down trunk floor piece you will have allowed yourself enough wiggle room to fit the tow control module in. You do not need to remove the entire side panel, just enough to squeeze the hardware in.
The AFTERSALES instructions direct you how to route the wiring harness and mount the tow control module. The tow control module has a prepositioned bracket in which the unit mounts vertically with the connections facing towards the center of the car. The bottom slips in to a groove and the top is secured by a nut and bolt (or a screw and the clip on tab-illustrated in the AFTERSALES instructions).
Once the tow control module is in place make sure the vehicle red connector and wiring harness are plugged in to it, then plug in the green pigtail into the green connector in the box behind and to the back of the CD changer.
Next, place the Pollack 7 blade electrical connector to the left (driver’s side) of the tow hitch. Run the wiring harness as far from the muffler/exhaust as possible. There is a heat shield (presumably to protect the bumper/rear parking sensors from the muffler exhaust heat. Run the wiring harness on the cool side of the heat shield and secure it as you see fit. Remember to replace the rubber plug in the hole you passed the wiring harness through. Replace the cream foam in the oval hole, the replace all the panels you removed to access the tow module controller bracket (Refer to Wayne’s write up.)
The final task is to appropriately secure the 7 blade Pollack electrical connector to the left of the tow hitch. I am still figuring the most esthetic way to do this with my CURT hitch. The OEM hitch makes it easy as there are mounting holes for the Pollack electrical connector’s bracket.
That’s it! I hope this summary helps anyone who decides to install the OEM surge brake system. The four major lessons learned in this project were
1) The rear trunk panel Is one pain in the butt to remove
2) OEM Porsche tow modules do not work with LED lights (NOTE: Porsche has known of this issue for some time and likely has resolved the problem for later Model Year Cayennes (circa 2012??)
3) I did NOT need to have the dealer program my tow module. Of course my Cayenne is a 2005 maybe other years are different.
4) I would recommend new hardware in this project, or at least inspect your wiring harness for any damage, and if buying a used tow module controller get a later version to eliminate the need to visit the dealer for a reprogram/reflash.
If anyone has any questions please feel free to ask me, I hope this helps someone
Photo of the wiring harness used
This Photo is of the tow module control unit prior to connecting to the mounting bracket. The visible connection is for the tow hitch retraction system. Not present in most of the tow module control units
Photo of the tow module control unit installed
