Before you go to work on the buzzer, check the drivers side door switch. Mine was not working when I got it, and I found that by moving the switch in and out, it would work. The switch has an extra set of contacts, on for the int light, and on for the ECU, so it knows if the door has been opened.
The Buzzer is under the dash, on the door side of the steering column, basically just behind the headlamp adjuster switch and mirror switch. It looks a bit like a relay and is held on with one screw.
Opps, sorry, just re-read and realised it's not a T2, sorry... Worth a look though.