2006 X5 Trailer Wiring Harness

[AVHemi]

I tried buying the BMW wiring harness for my trailer hitch, but they are all sold out. I am going to order the proper towing module, but I got an aftermarket 7 pin trailer connector and did my own wiring. I took pictures of how I did everything and will post them soon.

But I need to know if anyone has the pinout for the connector that is inside the trunk, behind the passenger compartment (where the fuse panel is located). I have the wires from the trailer connector inside the trunk and was going to connect them to the factory wiring harness with some butt splices.

There are 12 wires. I'm assuming that 6 wires are grounds, and the other 6 are tail lights, backup lights, right and left turns, electric brake controller, and power. Each with a matching ground wire. I just need to know what each wire is.

Can anyone help me? I've already searched the forums and it looks like no one else has done this yet. I have attached pictures of the connector that I'm talking about.

[JCL]

When you buy the BMW wiring kit you get a new harness that runs from the receiver (where it plugs into the back of the trailer wiring socket mounted on the receiver) to a 12 pin plug in the right rear storage compartment. That 12 pin plug is called X393s. You appear to be asking about the X393s plug waiting to receive that new harness. But the pin assignments won't help you. When you buy the wiring kit you also get the trailer wiring module which mounts under the spare tire. The module powers up the X393s plug, without the module that plug won't work.

Read the installation instructions posted here for more details.

http://www.bmwmotorsports.org/pdf/e5...iler_hitch.pdf

You need to be careful when tapping into the BMW vehicle wiring because it is multiplexed. Many have had problems with warning lights in the dash and faults in the lighting control module. Some haven't.

Edit: As an aside, the link includes the wiring diagram and pin assignments.

[AVHemi]

Thanks for the reply and PDF, JCL.

I have ordered the trailer module, from ECS tuning, to power up the plug (the one that goes under the spare tire). I am trying to keep this as factory as possible. That is why I did not order a generic tap module from any other company. I've read of too many problems.

The only this that I've done, is installed my own 7 pin trailer connector and ran wires to the passenger storage compartment to connect to the X393s plug. There are 12 wires in that plug and only 7 pins on the trailer connector. So somehow BMW has to get 12 wires down to 7. And one of those 7 pins is a ground.

[JCL]

As well as the module, you need part number 71600009698 which is the BMW number for the proper wiring harness.

Trouble is, the harness is listed at $164 and the module at $154. The whole trailer hitch kit (which included the receiver, draw bar, wiring harness, and module) is listed at $439. It is very expensive buying the pieces separately.

If you don't have an OE hitch, I would just buy the full kit and cancel your order for the module. Or find someone with an OE hitch kit so that you can unplug the rear harness and read the pin numbers (you can try and take them off the picture of the harness in the ECS catalogue, but you would have to use a test light and figure out which is which).

Also, the BMW wiring harness may have some combination of those 12 wires jumpered in the plug to indicate the presence of the rear wiring harness, and which harness it is. There were different rear wiring harnesses for different markets (North America, Europe, etc) with different sockets on the receiver. Specific plug jumpers could be used to identify that to the module IMO. At least that is the way I would design it. I can't see jumpers in the photo, but it is tough reverse-engineering this from a catalogue photo.

Good luck.

[AVHemi]

Actually the one for $164 comes with the module. The only problem is, it's backordered from BMWNA for who knows how long. So that is why I purchased the module separately, along with making my own wiring harness from the 7-pin trailer connector.

[JCL]

I asked that from ECS previously, as their photo showed the module along with the harness, but their quote on this site to another poster indicated that they would need the module as well. I didn't get an answer, as I recall. There is certainly more than $10 of value in the harness and grommet, socket, bracket, cable ties, and so on.

If you take the BMW part number from the ECS site, you can google it. I suspect Bav Auto, and others, have it.

Edit: Found the last conversation, here: http://www.xoutpost.com/bmw-sav-foru...g-harness.html