Seems like a common topic for the Jetta, but here goes. My 2000 Jetta VR6 seems to have a ghost residing in the inner workings:
1. Battery holds a charge for about a month. Battery checks out okay. No indication on the car that its not charging.
2. When idling, fan sound fluctuates with electrical load, lights dim.
3. Some mornings when you drive off and step on the brake, the radio cuts out, the ABS and brake light illuminate. Couple more brakes, those lights go out and the radio works normal for the rest of the day.
New main computer board replaced last summer, new brake light switch replaced then as well.