I have a similar problem on '04 X5 3.0. Rear left taillight wiring harness connector has a bad ground brown wire, which when I twist it makes a good contact & lights come on, but hard to keep in that position & lights go out. Dealer's asking $550 to replace the entire rear left light assembly & repair the ground wire. I know this is highway robbery. Does anyone know how I can replace the wiring harness connector? Please help, much appreciated.