[tmarshall57]

I bought a 2009 118d M Sport in January which had side bolsters that didn't work. Fuse 20 was missing and the bolsters worked perfectly when this fuse was replaced. This may be part of your problem. There could be other issues such as missing wiring but I can't add anything in that respect. Good luck.

 

[tmarshall57]

ISTA will have the wiring diagrams and plug pinouts for the 2 models/years you are dealing with. That could help point you in the right direction.

The black box: can you see a part number on it? If so RealOEM will identify it. If it is not OEM could it be a bypass for the occupancy detector? The occupancy detector mats have been known to fail.