Originally Posted by bluvalley

The plug for the brake controller is attached to the wires in the right rear panel, you might need to reach in pretty far to find it. It's got a small plastic bag attached with a plug inside. BMW does not have the wires labeled.

The brake control wiring needs to be run from here to the dash. I would not accept an answer like that from your dealer about the install, if they installed the hitch than they should install the controller. My dealer was not thrilled about it either but I pressed them on it and they did a really nice job, one of the service guys knew all about controllers from installing them in his pickup.

The total cost was about 350.00. The controller I have is the Tekonsha Voyager, they do not recommend the more advanced Prodigy model because of the X5's complicated electronics.

I don't have a pic of the wiring bundle but I've attached one of my X5 and Airstream.

Good luck