Originally Posted by dglcinc

Brilliant! That was the missing piece. I think because the BMW manual was written in 2008, that was before the turbo (?), so it does not have the detail about the inner port having a vacuum hose in it. I have the turbo model, which has a vacuum controller to control the exhaust port. THAT is what is going through the inner port on mine (as described in the manual you attached, which is more up to date.) That tells me what that thing is on the inner pass through, it's a vacuum hose. So, now I know that I need to reroute that though the outer grommet using a fish wire, and VOILA! All is as it should be, and I have the inner port available to install the hitch harness. Bless you. If you come within pouring distance I owe you a beer.

So did you get the retrofit coding for the hitch and if so who did it and how much?