Ah, the joys of owning a Volkswagen. Last week the horn on the B5.5 Passat TDI started beeping on left hand turns. Some compressed air behind the airbag fixed that. This week the turn signal relay started clicking by itself. I had a pretty good idea that it was the switch but I had a spare hazard switch which is also the turn signal relay so I replaced that first. I took a video showing the problem. Then I took the turn signal apart to clean it, problem fixed. You can sometimes get away with shooting some no residue electrical contact cleaner in the base of the turn signal stalk but I felt like taking it apart. The full writeup is below http://www.myturbodiesel.com/wiki/clicking-turn-signal-repair-or-hazard-switch-relay-replacement/ and has been added to the mk4 FAQ indexes. I'm sure the mk5 switch may do something similar but it seems to happen on mk4 switches a lot.