One problem related to turn signal flasher unit has been reported for the 1999 Volkswagen Jetta. The most recently reported issues are listed below.
Brake light switch replaced because cel illuminated indicating a failure of same. After some testing, it became apparent that the brake lights were not illuminating approximately 9 out of 10 times that the brakes were applied. At approximately the same time, the right turn signal began arcing. Replaced the right front signal bulb due to carbon buildup on the bulb. Also replaced the turn signal relay. Right outer cv boot was found to be leaking grease on 5/22/2002 and again on 4/29/2003; in both cases it was replaced. Battery died on 3/10/2003. On 7/9/2002, the center rear seat belt became stuck in its retractor and would not release. Seat belt assembly was replaced. On 10/1/2001, the driver's front window regulator was replaced after the window fell into the door without warning.