I have a 1992 passat 2.0 litre. I recently replaced the heater core and noticed that my alternator no longer is charging and my battery light on the dash doesn't turn on. When the car is running I can apply power to the D+ terminal of the alternaator and it then begins charging. Could I have disconnected the blue D+ wire under the dash? I'm wondering where I could access it and how I would test it. Also, where does it power up from? Also, There is a relay (#35) mounted behind the ashtray in the console that is constantly "clicking". Would anyone know what relay this is and what may be the problem? Thanks in advance for any help.

 

the clicking is probably the voltage regulator clicking a relay on then off rapidly as the charge from the alt. is not being accepted by the battery or has no where to go. the relay is telling the voltage regulator that the battery is fully charged and to stop sending power to the battery. does the clicking stop when you connect that + wire? sounds like you guess is right that you may have knocked off a wire and interrupted a circuit.