rosneri

While this seems to be a complete mystery to VW dealers (but for the fact that mine decided to do the research), there is a four wire harness under the dash on the driver's side that is intended to hook up to an electric brake controller. The plug connects with the trailer hitch control module that is mounted in the rear of the vehicle when the hitch is installed. The VW dealers should have the wiring diagrams that explain which color wire corresponds to the power, ground, brake light switch and trailer brake wires of the controller. Unfortunately, my dealer indicates that they don't have the matching version of that plug to attach to the controller. However, it would be a simple matter either to cut the plug off and splice the controller directly to the wires or add a new plug sourced from Radio Shack. The beauty is that there is no need to run lines to the battery, splice into brake light switch, etc.