i had problems with failed brake light on my 300tdi just before xmas. it turned out to be a fault with the little steel 'wires' on the back of the light cluster that go to the bulbs. it was very slightly corroded (white colour) but still didnt work even when cleaned up, even though i could get a voltage when touching the surface of these wires on the back of the light cluster, so i ended up changing the whole cluster which solved the problem. it took me about four hours checking everything from fuses to trailor sockets, bulbs, wiring thinking it was the crappy scotch locks attached to the cluster wiring. i was pleased as punch when i got it working again cos it was about -1 while doing it :dizzy: