I have a 2005 X3 with 3.0 engine I have the factory hitch assembley with wiring harness and connector etc My question is how do I go about connecting a Trailer brake control to the system The BMW trailer hitch electrical connector has a pin for Brakes but has volts every time the brakes are applied and that will ock up the trailers brakes full on. I need to regulate the voltage with a brake control ( Prodigy Brake control Electronic NOT hydraulic) Anyone out there know how to go about doing this. Dr Dave