Hi, I had exactly this problem with my 4motion not so long ago. It took three visits to local stealers to eventually get it sorted... The problem was supposedly intermittent according to them as far as I was concernened when you took the key out of the ignition left the lights on and opended the drivers door the buzzer should have worked... it didnt and I had to sit a 'techie' in the passenger seat to demonstrate this for him to believe me. [V] Anyway long story short, eventually they sorted it under warranty... isolated it to a switch in the drivers door think... you will certainly not need a new dash, and also I don't think the Mk4 uses the same buzzer as for the Handbrake/boot open/ passenger door open sound, it is more of a hollow drone!!! I'm popping into stealers tommorrow ans will ask them to bring up the repair details for me. Soon as I have them will give you the proper answer. Annoying when u 4get to turn your lights off and your battery goes dead isn't it!!!![V]
I know it's taken a while, and you have probably sorted the problem now but VW have erased my log from their computer!!!! [:O] bizarre.. however the mechanic who did the job was there to speak to (after I proved to him that i did genuinely have a problem with it)
He told me the problem ended up being the drivers door lock mechanism. I think it caused some kind of electrical fault... If you have a warrenty, then they should sort this at stealers, however as I wasn't sure when I told him that 'a mate was having the same problem' the guy tried to offer me a foreigner for lot's less money!!! so if you are anywhere near Crewe stealers LC Charles, then I can pass you his contact number and he will do the job cheap!!! (Apparently a fiddly job??)
Many thanks Evilhomer. Much appreciated. I did a bit of research, checked all the fuses and bulbs again and came to the same conclusion as you. I bought the door lock module from the stealers yesterday (?85) (with the de-lock kit) and with the help of the vwvortex guide, I'm going to try and fit it this weekend (weather permitting).
No Probs Morse, anytime.. at least what ive told you confirms your thoughts.  Good Luck.. personally I would have done the job myself too... Stealers mechanics... like trained monkeys!!! that's an offence to monkeys!!![)]
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