The cover above holds the diagnostic port for the MOST fiber. That is where you hook up to update the software for the car. The fiber is a loop and needs to be connected in a loop for all components on that loop to function.

Pre-LCI items on the loop can include the CCC head unit, Logic 7 amp, TCU (SOS and BT phone), MULF (USB), Sat tuner, HD radio, DVD changer, heads up display

__________________
2009 35d, 2006 325i & 330i