Electrical issues that are difficult to diagnose—and sometimes intermittent—are typically due to ground wiring issues. The most troublesome ground locations are under the battery or at the engine.Google+
Car Problem Reports
Volkswagen Jetta TDI Difficult to Diagnose Electrical Issues Are Typically Due to Ground Issues
Volkswagen Jetta TDI Problem
Average Mileage: 177,800 mi (65,000 mi - 261,000 mi)
Visitor, 2005 Volkswagen Jetta TDI, 140,000 mi
more and more frequently, i get in the car to start it and i notice that the clock is at 1200. the trip odometer is at zero. the overall odometer reads the mileage. turning the key will make( on occasion) a ticking sound. not always. after turning the key on and off several times the car will start. this is a tdi by the way. if i don't get the glow plug light, it won't start.
Visitor, 1999 Volkswagen Jetta TDI
This is a 1999 Golf Automatic (Gasoline.)
The car will not start despite charging up the battery. The starter will click but will not turn over.
Te rear window wiper will not turn off when switched to 'off'
The engine would cut off completely in random locations but most notably in the fast lane on the highway. The wiring harness had to be replaced for the engine and it was covered under warranty.
Visitor, 2003 Volkswagen Jetta TDI, 188,000 mi
front and rear light bulbs burn out too often