Originally Posted by Weasel

Same diagrams, the online WDS wiring diagrams is the same thing the dealers get directly from BMW. That's what I have to work with all day. But if the installer doesn't seem to know off hand what to do in a BMW, DO NOT USE HIM!!!

I have seen and had to repair so many butcher hack jobs done by BS installers that think it's ok to cut and splice wires etc. It would really be worth your time to find someone with good BMW experience, access to the right resources like the WDS, and know how to make their own pigtail harnesses if necessary. (like I have done on all my BMW accessory installs) and knows not to cut/splice any wires.