Install the 7 pin trailer lights for BMW X3 E83

October 7, 2014 / Posted in  Cars

If you already have a hitch installed with no wiring and you aren’t sure you’ll need the 7 pin wire connector, you might want to start with the 4 pin connector which I had installed at Road and Rack. It’s not OEM like the 7 pin install detailed above, but this will integrate nicely with the X3 computer system and not throw any dashboard warning lights after install or during use:

If you need help installing the Curt 59200 Converter and Wiring Kit, click here for instructions. If you guys need me to tell you the specific wire colors, leave a comment below and I’ll add any additional info you need.

Upgrading to the 7 pin connector and adding a Brake Controller

To upgrade to the 7 pin connector, you only need to add a 7 pin connector like the Hopkins 47185 Multi-Tow Adapter. 4 wires are already covered, you just plug the Curt’s 4 wire plug directly into this unit. The last 4 wires you need to supply are power, ground, reverse (or aux), and brake power. Power and ground should be easy since the battery and 4 pin integration is presumably present. That leaves reverse and brake. The reverse signal is in the passenger well, you need to remove the cover and splice into the green and yellow wire. You also need brake, which is the black and lime green stripe wire. I’ll take a video and post it below to provide more context.

To make the install more professional and to help protect from warning lights on my dash, burnt fuses, or computer glitches – I used auto relays. I provided a diagram below of how I wired everything up, if you have any questions just leave a comment and I’m happy to explain more. Hopefully the diagram and video will be enough for everyone. If this article helped you out or you have some suggestion, feel free to leave me a comment.

How I wired in the brake and reverse signals to the 7 pin trailer connector using relays

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