Erratic turn signal operation can be a result of a failing turn signal flasher relay which will require replacement.Google+
Car Problem Reports
Volkswagen Jetta Flasher Relay Failure Can Cause Erratic Turn Signal Operation
Volkswagen Jetta Problem
Average Mileage: 99,266 mi (45,000 mi - 220,000 mi)
Visitor, 2002 Volkswagen Jetta, 90,000 mi
Flasher keeps on ticking NON-STOP whithout the flashers actually lighting up.
Visitor, 2001 Volkswagen Jetta, 62,000 mi
turn signal sound goes on at random moments,but not the actual signal
Visitor, 2003 Volkswagen Jetta, 125,000 mi
Had to replace the Flasher Relay, quick easy fix... just annoying
Visitor, 2001 Volkswagen Jetta, 115,000 mi
Erratic clicky-sound of the turn signal, yet no visible/physical problem with the signal. Just an annoyance.
Visitor, 2002 Volkswagen Jetta, 60,000 mi
Turn signals stop working completely during driving, sometimes producing a constant tonal noise, other times no noise. The a/c stops working at the same time.
Visitor, 2000 Volkswagen Jetta
Turns signals stopped functioning properly and began to stick on or off.
Correction was done by dealer under recall.
Visitor, 2000 Volkswagen Jetta, 90,000 mi
No signals of hazards. VW JUNK!
Visitor, 2001 Volkswagen Jetta, 110,000 mi
Turn signal clicks like a mad man on crack. Not repaired.
Visitor, 2002 Volkswagen Jetta, 70,000 mi
blinker clicking noise randomly would go off,found it to have a short in the wire.
This problem began at 50000 miles!