Cayenne 955-957 2003-2010 Series I
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Experiences on installing Cayenne trailer wiring

Old 10-29-2010, 10:10 AM
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Default Can't speak about the exact wiring but the rest is accurate

Originally Posted by Aremee View Post
I tried following the instructions, and nothing about taking the panels apart seemed to be accurate. Couldn't find any access panel to the left of the spare tire compartment, not sure if I needed to remove the OEM Bose sub woofer that is underneath the tire. On the left side of the car, which I figured was the passenger side, it wasn't identified, I have a CD Changer, again, OEM, and the shelf that is described is impossible to get out as described when there is a CD changer. I am just wondering if the wiring described in this post is even accurate before I start trying to wire my hitch. Any comments would be appreciated.
The left side is the drivers side in the US
The access panel writen about is more like a piece of the floor just to the left of the spare tire well.
I used these instructions to install a 12volt battery run for my trailer winch and found them pretty accurate.
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Old 11-10-2010, 06:38 PM
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I don't have a CD Changer or Subwoofer. On the left (or drivers side) at the rear, I have a storage compartment that is reasonably easy to remove as per these instructions. You can catch a glimpse of it at the extreme right side of the picture I posted (in black). You may want to update this post once you or a professional installer performs the wiring hookup with a CD changer.
I expect that if the CD Changer is in place of that storage shelf, then that changer is going to have to come out in order to access the wiring connections.
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Old 03-28-2011, 08:48 AM
Shawn Stanford
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My brother (and I, but mostly my brother) completed this installation using the Tow Ready 119146 Upgraded Modulite Vehicle Wiring Harness with 4 Pole Trailer Connector. North's instructions were complete and easy to follow. The only difference is that instead of wiring to the battery, mine is wired to the driver's side cargo area 12v plug.
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Old 07-02-2011, 02:03 PM
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I want to highlight my experience installing a CURT hitch on my 2005 Porsche Cayenne and the Porsche wiring harness and control unit. I bought a Pace trailer and wanted the lights to work, so I installed the Porsche OEM wiring harness and new control unit.

You will need these parts:

1) Porsche Part 955-618-040-10 Control Unit

2) Porsche 955-612-506-00 Wiring Harness

3) PNA-955-118-93 trailer hitch Connector (this is the 7 pin Pollak connector) This is where the factor wiring harness plugs into at the center of the bumper hitch location so you can plug in a trailer harness. This is just a socket connector, weatherproof with a cover)

4) PNA 955-127-08 7-4 way Adapter (this just converts the 7 way adaptor to a 4 pin adapter)

PNA-955-118-93 is the same thing as Pollak 11-893P 7 way sealed RV OEM Socket that you can buy on for 11.60
Also will need Pollak Mounting Bracket for Pollak 7-pole Rv Style Trailer PK12711U

First, you should have the proper tools to take off plastic trim pieces without breaking anything. You should have patience and have experience working with cars, otherwise this can turn out to be a very difficult project. Not for a novice.

To remove the bumper you have to take off the taillights since there is a screw located there. Then there are screws found in the wheel well and under the bumper. There is one screw in the wheel well that is hidden from sight and you have to bend the plastic trim piece to get access to it. After removing the bumper you will see the location of large bolts on each side of the metal bumper that you will remove and then install the Curt hitch. The Curt directions are good so use that has a guide.

As for installing the Porsche wiring harness this is what I noted. The wiring harness itself is simple to install since the connectors just snap in. One connector is colored green and this matched the green socket that it plugs into and the other black connector goes into the new control unit. There is already a purple connector prewired in the cayenne that plugs into this control unit. Once you have these plugged, everything will work when a trailer is connected to the car and only if a trailer is connected to the car. The control unit can sense if something is connected.

Getting the wiring harness and control unit installed was a little harder. If you don't have a CD changer installed you should be able to use remove the little trim piece in the truck on the passenger side , it just comes off, and reach in there and install the new control unit and plug the new wiring harness into this. You can see the prewired purple connector sitting there wrapped in grey foam and it's located right where the control unit will be installed. However if you have a CD changer you will need to open up trim pieces and this is the hard part.

One way to do this is to take out the carpeting in the trunk floor, you will see screws for the tie down clips and 1-2 other screws. Then you will see screws for the sidewall carpeting. Then take off the top center light located on the ceiling, and pop off the top passenger side trim using plastic trim removal tools. Be very carefull because if you use too much force you will break the plastic clips on the trim pieces. There is also a screw on the side wall coat hanger. After popping off the side trim piece near the window (d pillar) you can bend the side carpet trim piece in the trunk outward so you can get you hands in the location of the new control unit mount. There is a piece of black vertical plastic that the new control unit just gets attached to with 1 screw. Very easy and the location of this is exactly where the purple connector is, which is wrapped in grey foam.

Lesson learned,
I could have installed the control unit without removing the carpeting and trim pieces, but I didn't know better. The location of the new control unit mount and the purple connector were visible and I could reach it with my hands.

Using the factory wiring harness and new control unit work great. There is no need to program anything using a Porsche computer. Everything was plug and play.

The time I spent doing this was not worth it. It would have been better to get the parts on my own and just give it to a dealer to install or have an aftermarket porsche guy install it.

Unless you like to work on your car and don't care about how long it takes, it's worth it to pay someone to do it.
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Old 07-07-2011, 08:44 PM
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You will also need these two parts to install the 7 pin socket to the back of the car. The PK12711U mounting bracket is a metal bracket that perfectly fits the pollak socket and since it's very hard to drill into the metal of the Curt trailer hitch you are better off getting part 18140 which makes the install very quick. If you have all these parts then the installation will go very smoothly.

PK12711U Mounting Bracket for Pollak 7-Pole, RV-Style Trailer Connector - Vehicle End

18140 No-Drill Mount Bracket, Short
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Old 05-12-2012, 05:06 PM
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I was out in the garage hacking my way into the tail light housings, and running wires back from the tail light sockets when I found this post. A much nicer approach !

I'm going to start over and try this route. Will post results when I get it done.

Many thanks !
2006 Cayenne S
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Old 05-19-2012, 08:02 PM
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Thanks for the good ideas !

I had trouble getting to the wiring harness on the left side, so did most of my install on the right side.

When you remove the right side "cubby cover"' you have access to all needed wiring, except for the left turn signal. For the left signal, I again removed the "cubby cover" on the left side, and then removed the two torx bolts holding the interior shelf in place. The shelf material is flexible, so you can pull it aside to get to the left turn signal wire. I then only had to run a single wire from tHe left side over to tHe right.

Power on my car was available via a 12v outlet that shares an access port with the signal harness. I tapped off a brown and orange wire with good results. I secured the controller on the bottom of the right cubby, with everything tidy and out of sight. Cable for trailer stows nicely next to the spare tire.

$1400 trailer tow package for less than $300, and about 4 hours of labor (including hitch install).

Thanks again for all the tips,
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Old 10-26-2012, 08:47 PM
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Default Porsche Cayenne: Adding a flat, 4-wire trailer light connector to the existing 7-wire

Porsche Cayenne: Adding a flat, 4-wire trailer light connector to the existing 7-wire trailer harness.

Before you start slamming me for not buying an adapter and for modifying the existing wiring, note that I looked and couldn't find one locally that would fit. I needed to pull a u-haul trailer on very short notice, so I had to improvise.

My boat trailer has hydraulic surge brakes so I needed only basic trailer light wiring. I first added a 4-wire connector to my 2008 Cayenne in an emergency situation and it worked out so well that we did the same to my buddy's 2011 Cayenne S. Both came with a factory receiver hitch and 7-wire socket. We had trouble finding a 7 wire plug adapter that's an exact fit for the socket, so we set out to decode the vehicle side wiring. If yours is a different configuration or different year model, I'm not promising this will work for you. The Cayenne's electrical system is complex, so it took a bit of time to grasp the syntax, but in the end, it cost only a few bucks for a 4-wire connector and it's worked like a charm. The vehicle's computer will even tell you if you have a bulb out on your trailer.

Detailed below are the 4 wires that you'll use to add a basic 4-wire trailer light connector to your Cayenne. The 4 wire connector will provide power for:
running/tail lights, left turn signal, right turn signal, brake lights and emergency flashers.

Vehicle wire colors used in this application:
Large Brown - Ground (Note: Do not ground to vehicle body or frame. See below)
Green - Tail/Running lights
Small Brown - Right Turn/Brake Light/Emergency Flasher
Red - Left Turn/Brake Light/Emergency Flasher

*The vehicle-side wiring harness contains 7 total wires. You'll use 4 of those wires for this application. The other 3 wires (I don't remember the colors) are for back-up lights, electric brakes, and a fused continuous (even with ignition-off and key-out) 12v supply for things like chargers or ignition-off lighting.
*This application is for incandescent trailer lights only.
*Non-resistor LED trailer lights will not function with your Cayenne's wiring system.
*Grounding: For trailer lights to function, you'll need to connect the Large Brown wire on your Cayenne to the white wire (ground) in the 4-wire connector. (The Cayenne's computer is polling for an electrical load, measured relative to the Large Brown wire. A electrical load is required to activate power to the trailer lights, so if you attempt to use the vehicle body or frame as a ground, your trailer lights will not function.
*The Large Brown ground wire is too large for the crimp-type connectors that I had on-hand. (I stripped a 1" section and used a pencil iron to solder it to the white wire (ground) from the 4-wire connector.
*Use ONLY a 12v incandescent test light. (a non-resistor LED test light will not work. A multi-meter, set to measure voltage, will not work.)
*Your test light will not immediately illuminate when connected. The vehicle's computer needs a couple of seconds to detect the presence of an electrical load and to power up the circuit, so be patient.
*For insulating connections and for sealing and wrapping the added wiring, self-fusing rubber tape such as Scotch 70 is an excellent choice for this application. (Adhesive backed electrical tape gets sticky over time and doesn't provide long-term moisture resistance.)
*This wiring does NOT support electric brakes, backup lights nor auxiliary 12v power to your trailer.
*Be smart: park in a level spot, set your parking brake, chock the wheels, get the game going on the radio, invite a buddy over so he can visit with you and hand a beer to you while you work.

1. Remove the 4 screws from the 7 wire socket that's located under the bumper, just to the left of your trailer hitch. The vehicle-side wiring is pretty short, but you should be able to pull enough wire down so that you can see the wires running into the back of the 7-pin socket. Remove the cover from the socket so that you'll be able to access the terminals inside with your test light.
(If you're a trusting soul, you can skip steps 2-7)
2. Turn on your park lights. (no need to turn on the key at this point)
3. Touch the probes on your 12v INCANDESCENT test light to the terminal associated with the large brown wire and to the terminal associated with the green wire. Within a few seconds, the test light should illuminate.
4. Turn your ignition to the "on" position and turn on your left turn signal.
5. Touch the test light probes to the large brown wire and to the red wire terminals. Within a few seconds, the test light should begin to blink.
6. Turn on your right turn signal.
7. Touch the test light probes to the large brown wire and to the small brown wire terminals. Within a few seconds, the test light should begin to blink.

8. You're going to need more slack in the wire to add the new wiring, so look up, under the bumper and find the closest plastic anchor point for the trailer wiring harness and pry it loose, or just cut the cable-tie.

9. Use wire taps or, as I did, strip and solder and then tape the wires in the following combinations:

Large Brown wire on vehicle to White wire on 4-wire connector
Green wire on vehicle to Brown wire on 4-wire connector
Small Brown wire on vehicle to Green wire on 4-wire connector
Red wire on vehicle to Yellow wire on 4-wire connector

10. TEST: Go through steps 2-7 with your test light, but check them at the terminals on the 4-wire connector OR, If your trailer's handy, plug it in, hand a beer to your buddy and ask him to help you run through the test while you watch the lights on the trailer.
12. Finish up. Tidy up your wiring and use a zip tie to anchor your new wiring to the 7 wire bracket for strain relief.
13. Replace the 7 pin connector cover and screw it back into place with the four screws that you removed in step one.
14. Put away all of your tools, hook up your boat and head to the lake, comfortable in the fact that you've just successfully modified the wiring on a VERY expensive European SUV.
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Old 07-07-2013, 11:08 AM
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Originally Posted by Shawn Stanford View Post
My brother (and I, but mostly my brother) completed this installation using the Tow Ready 119146 Upgraded Modulite Vehicle Wiring Harness with 4 Pole Trailer Connector. North's instructions were complete and easy to follow. The only difference is that instead of wiring to the battery, mine is wired to the driver's side cargo area 12v plug.
Like Shawn Standford & brother, I followed North's instructions, using the Curt adapter, and pulling 12V from the accessory socket, rather than a direct run to the battery. Those rear 12V accectory sockets share a 20A fuse, and are fed with wiring plenty large to run trailer lights. Just don't dry to run something with a heavy load off the sockets while you've also got your trailer brakes on, and everything will be fine.

This was on a 2005 Cayenne Turbo, with factory Bose subwoofer (under the spare), CD changer (in the right side cubby) and factory air suspension (pressure tank to the left of the spare tire). I also located the adapter on the back left side of the spare tire well, and just tucked the 4-wire lead into some remaining space under the spare tire well cover.

The computer displayed a single error message to the effect of "current draw with key off" when I initially inserted the fuse for the adapter power. As a sanity check, I measured the key-out current draw of the unit, using a mulimeter, and it's zero milliamps. Perhaps there was some higher initial draw for charge a capacitor or something, but at any rate, I'm not going to worry about it. There haven't been any warnings since then, and it's working great.
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Old 07-27-2014, 03:56 PM
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Just did this install so I can tow my Kayak trailer. Worked like a charm, no errors. Thanks fhr the help.
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Old 04-22-2015, 03:25 PM
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Default Does the same 56146 unit work on 2014 cayenne

Does the same 56146 unit work on 2014 cayenne
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Old 07-18-2017, 09:33 PM
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Ran into this 7 year old thread while searching for instructions on the installation.
400North, your instructions were spot on. Thank you so much !

2006 Base Cayenne.

Installed the Curt Class III Square Tube Hitch (Part #: 13220) and CURT 56146 Powered 3-to-2-Wire Taillight Converter.

- connect the green trailer controller wire to the black with green stripe right turn wire of the taillight wiring harness (passenger side)
- Yellow left turn wire to black with white stripe wire (driver side)
- Brown running light wire to gray with black stripe wire (driver side)
- Red stop light wire to black with red stripe wire (driver side)
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Old 08-13-2017, 11:38 PM
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Default Control unit issue???

I'm having a strange issue with my wiring install and I'm wondering if it's my used control unit. When I pin test at the 7 pin connector I get a very solid full power signal but then if I touch the running lights, after the delay it gives a pulsing signal, not constant like it should be. My turn signals both after the delay give a random flash as if (like the running lights) it's just not giving a constant timed flash like they should be. I had someone with a cayenne send me a video of pin testing his plug and his was giving him a nice solid signal compared to my tests. I have a non led utility trailer that my car will not light up at all. It's worked with a 7 pin pontoon trailer. If I plug my trailer and 7 to 4 pin adapter into my neighbors pick up, the trailer lights work just fine. I've had my car programmed at the local Porsche dealer but it didn't change anything. I'm working with the seller of my control unit to see if he has another one I can plug in and try. Any other ideas???? '08 Cayenne
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