Sorry for the late response; it's been some time since I looked at this forum. My car is a 92 300E sedan. I had a similar problem several years ago, and found that the wire to one of the plate lights had an intermittent open in it. The bad news is that these lines (there is a separate hot line for each of the two plate lights) pass through the left tubular support arm of the trunk lid hinge. I had to pull the wires out and splice in new sections. Before you jump into this, check two things. 1) Make sure that you have a good ground at each of the bulbs. 2) Check the continuity of the wires while applying some tension to verify that you have an open in the wires. You will need to remove the lid liner to do this. If you find that you have to pull the wires, be sure to attach a strong string or single strand uninsulated wire to the end that is being pulled through the arm. This gives a way to pull the repaired wires back through the arm. Failure to do this will spoil your whole day! Good luck!