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.

 

Thanks, the bolsters worked before but will check

 

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.

 

Unfotunatly ISTA will have diagrams only to connectors before yellow plug. Rest you must figureout by yourself.

 

The part number for the black box is 692643501 and looks to be heated seat control. Would be nice to get working but looking at a couple of threads it looks very involved so will gove that a miss!

Would like to get bolsters working if there is a quick fix though!

 

according diagrams the pre-2007 cars had bolster adjustment powered with seat adjustment via PIN9
later it uses PIN7 for that job, now separated from seat adjustment
but anyway even docs have errors and it is better to undo tape and trace wiring from bolster/lumbar connector to seat connect to doublecheck that
after that you need to perform adjustment as needed.

 

Thaks for the reply and sorry for slow response - christmas and general family life put this little project on hold but im going to look into it as you say when i get some time and report the solution (hopefully!) back here. Cheers

 

Just to update this thread if anyone else looks.

As per ptpending advice when ive checked them all and routed the wires the newer seats use pin 7 instead of pin 9. As im not trying to use the heated seats etc ive simply cut the two wires and joined the wire going to pin 8 to the wire coming out of pin 9.

All works - cheers!