Hello,

this noise normally appears when the headlights are on and the door is open. In you case there seems to be a fault because the sound appears even when the headlights are turned off. The sound comes from the instrument cluster (KI). There is a little beeper in there.

I think there is something wrong with your light switch, or with the harness that leads to your light switch. To check that you'll have to take a look in the workshop manual and check which cable is giving the signal from the light switch to the KI.

Hope that will help.

Regards
Markus