Car wiring diagrams: Bmw X5 Wiring Harness Trailer, wiring diagram, wire wiring harness, schematic circuit diagram, wiring diagran, wireing diagram, wirring diagram, wiring daigram, wiring diagrams. i just purchased a x. it came with the trailer hitch, but there isnt any wiring harness. is this something i can purchase myself and install or do i .This hitch is for the X non M Sport Pkg , and it includes a wiring harness for trailer lights. The hitch bolts on easily and offers a nice, clean look . Video embedded . tv wiring_install__chevy_sliverado.aspx Videos are provided as a guide only. Refer to manufacturer installation instructions .