ard,

You would think that the trailer brake wiring would be done with the initial install but with BMW they only do it when you have them install their trailer brake controller.

Oaktree,
you do not need the extra harness with the wireless brake controller. That harness runs wires from the front wired controller to the back. They have to do a lot of work taking things apart to run the wires from the front to the back. You will need some extra wiring but not the whole thing. I will post some instructions when I get home.

Chuck