Hitch Installation

[phuksi]

Let's see how this installation goes... I will install a detachable aftermarket hitch made by Westfalia onto my X3. I did not buy the electrical kit since it was so expensive and the installation was quite complex and most likely it will not even work properly. The reason for it not working is that my car is NA model and I have brought it to EU (the kit is for EU models) and the LCM and signals for lights are different in these regions. So I will do my own wiring.

Anyway, we'll see how it turns out.

- p

[RastaGurl]

GL with the install, and post pics!!

[phuksi]

Ok here we go. First, a big thank you to x3eme for creating such a complete DIY for hitch installation. Removing the rear bumper was really easy with those instructions.

So I started by removing the rear bumper at 9 pm. That took about 45 minutes and the trickiest part was to pull the sides away from the vehicle body. I did not want to use too much force and you can actually release the locking mechanism with a flat screw driver once you have pulled the bumper a little out.

Attached a couple of pics with the rear bumper removed and the hitch installed. Initially I also installed the electric plug into the standard location defined by the hitch manufacturer. To get to this point it took about an hour and a half plus some satisfaction beers for another hour.

[phuksi]

So the next morning the assumption was to modify the bumper and cut it where needed and then put it back.

I decided to cut the bumper after it has been reinstalled. I lifted the back a little to get more room to work under the car. But then it turned out that the bumper won't go back. The hitch is too big to fit inside the bumper. It has been designed for the black Euro bumpers that are standard here... Oh well, I needed to remove the bumper again and cut small pieces away from the hitch.

While the bumper was almost in place I also realized that to be able to use the electric plug I need to cut a BIG hole that would be visible. I did not want to do that so I decided to do it my own way. Time to have a thinking beer.

Below pics trying to install the bumper and then it removed again. Also showing the places that needed to be modified on the hitch. I did paint the cuts to prevent rusting.

[phuksi]

Once the hitch was made BMW compatible it was time to redesign the plug holder. In the previous posts you can see the std installation and below a custom made from acid proof steel. This is the way I left it but most likely I will adjust its angle to point little backwards since it is now fully pointing down and there may be a clearance issue if driving over a curb.

[phuksi]

And finally this it what it looks like. You cannot see the cuts in the bumper when looking at the car from the rear unless you bend. The plug is visible and I will lift and angle it a bit to make it less visible, increase clearance and make it easier to use.

To get to this point it took me the whole day with some barbequeing in between and enough thinking time. I am quite happy with the results so far.

This was only the mechanical part of the installation. I still need to figure out the electric piece and how to get the signals to the hitch.

X3 has a weird way of using high frequency pulsed signal for the driving lights in the back (as well as for the yellow lights in the front). It averages to 3.4V but in reality fluctuates between 0 and 12V very quickly. When braking it increases the voltage to steady 12V. I need to get 12V for driving lights to the trailer, 12V for braking and both have their own pin in the plug. I have measured the connector for trailer module and now need to design the electrics to get the proper signals to 7-pin the trailer plug.

Does anyone know where I could access the third LED brake light cable? That would be the easiest way since it is not lid unless you brake.

[phuksi]

So the questions I have so far are:

1. where could I access the 3rd LED brake light cable other than in the tail gate? What is the color for the wire?
2. where could I access the license plate light cable other than in the tail gate? What is the color for the wire? I am not 100% sure if I understand the WDS coding.

The plate light is continuous 12V so it would be perfect for the trailer driving lights. I think the wiring goes in the left side of the vehicle but are there any connectors available (I did not find any) and which cables those might be? There is a module in the rear end and left side on the roof where the brake light connects but I don't feel like removing everything just back trace the cable.

Any help would be highly appreciated.

- p

[Shamrock]

Good improvisation. Appreciate the info as I'm considering installing a hitch. I don't have answers to your electrical questions, but have some info for future reference to anyone doing an install in the future. It appears that you also have the Sport Package with the body color bumpers. It appears that BMW makes a replacement for the black, bottom trim strip for X3s with trailer hitches. If you go to www.realoem.com/bmw/select.do , enter the last seven of your VIN, you should see a screen with all the data on your X3, go to the bottom of the screen and click on "browse parts", click on "51 Vehicle Trim", click on "51 15 Bumper", go to the bottom set of pictures and click on "Mounting parts for M Rear Bumper Trim". This parts list shows the bumper parts with and without the trailer hitch.

[phuksi]

Good idea. Here are the part numbers:

51123417077 Diffusor with a hole for hitch, about $50
51123414413 Cover for the hole, about $20
51127070204 Clamps to hold the cover (2 needed), about $1

I need to check what those prices are for me here... I bet they are a lot more... But that is an easy way of making a clean installation.

- p