This bulletin applies to Volkswagen vehicles equipped with the TDI engine. Under certain conditions you may hear the Glow Plug Relay J52 clicking on and off after the engine is started.
Once the engine is started, the after-glow period could last up to 3 minutes or until the engine coolant reaches a temperature of 140 degrees Fahrenheit and the engine rpm are below 2,500.
Under these conditions, you may hear the relay clicking on and off while shifting. This is because the rpms are going above and below 2,500 rpm. The relay is located in the plenum, near the wiper motor.