If your lights on buzzer doesn't work either I suspect it is the door contact switch that is at fault. On the front doors the switch has 2 contacts, from memory one contact does the door open indicator and the courtesy light, the other the puddle lights and lights on buzzer. I'm not sure about the rear ones.
The door contact switches are part of the door catch. Theoretically they can be changed without changing the entire door catch but I don't think they are listed as seperate items. Either way it is a complete door dismantle to get to
