I thought I was so smart when I replaced the trunk light bulb in my new (to me) Z3. I did notice, briefly, when I removed the light, that the wires were not connected. I thought I might have pulled it out too roughly. So, I put in the new bulb, connected the wires, the light worked, and I closed the lid. I guess I was not surprised, when I next tried to start the car, to find the battery dead. After a jump start, all was fine. When this happened a second time, I realized that there was a problem. Likely the slight switch was faulty. But where is the switch? My new friends at the local BMW parts counter knew the answer - the light switch is built into the trunk latch mechanism. For the small price of about $50 and 15 minutes of my work, the new trunk latch is now installed. This time, when I put the light bulb into the holder, I could hear the micro-switch making and breaking. The problem seems to be solved.