Not sure if this will help but I just had a problem with my brake lights, plate lights and even the dash lights would shut off. After working through the problem with a mechanic we were able to trace the problem to the worn out wires on the left hand side going to the trunk lid. We peeled back the rubber covering on them and right at the obvious bend there was almost seven wires that were fraid.
Not sure thats the problem but give it a check.
<img src='http://img76.exs.cx/img76/3617/bmw2a6ta.jpg' border='0' alt='user posted image' />
xmas-gifts smoked corners and spoiler...to be added.