it was my euro fog light switch.
http://i273.photobucket.com/albums/jj219/ceedeefl/f7e9_1.jpg
as far as the upgrade of the rear lights goes, it is a piece of piss. even a monkey could do it.
buy some euro rear lights... and pop em in.
but, i did a little bit of a different approach here.
i took out a rear light from my trusty old 5 series parts car.

and then using my dremel tool i cut out two light sockets. with the contacts and all.
then i got my rear lights from my 850ci out and dremeled out the spot for the new light sockets. (they are all the same size).
http://i273.photobucket.com/albums/jj219/ceedeefl/mtdorameet08001.jpg
so all i had to do is drill along the surrounding of the socket until it was lose. i then took the socket from the 5 series and glued them in place in the 850ci rear lights.
http://i273.photobucket.com/albums/jj219/ceedeefl/foglights001.jpg
then i soldered in a yellow and a brown wire (didn't have to but i thought it looks better having it the way it was supposed to be) and connected the wires to a pin i took out of the 5 rear light. since i used the whole socket, i didn't have any fitting problems with the new bulb.
http://i273.photobucket.com/albums/jj219/ceedeefl/foglights004.jpg
(why are my reflectors brighter than the fogs in this pic??? )
i installed it all and for the first time i don't have that pesky
'r/light failure' coming on anymore.
http://i273.photobucket.com/albums/jj219/ceedeefl/foglights003.jpg
now i only have 500 million more things to do before the next meet