Trailer Hitch Problems [Archive] - Bimmerfest - BMW Forums

: Trailer Hitch Problems

01-17-2008, 11:02 AM
1 does the wiring harness required to be reprogramed after install on 2007 x3 bmw?
2 has anyone out there install electric trailer BRAKE unit on there bmw and if so were did you fined the plug or wire up the control for the brake controller

01-17-2008, 12:49 PM
Wish I can help but I can't, although I will tell you that if you try to connect a trailer with electric brakes, or electric over hydraulic brakes, and the X3 is not wired with an in cab brake controller then the second you apply the X3 brakes the trailer brakes will lock up and you will smoke the trailer tires. There is no middle ground in the circuit, they are either on or off.

After trying to use the wife's X3 to tow my boat 1 mile down the road and experience the lock up I threw in the towel and never tried to add a brake controller...

Good luck!