Originally Posted by Grovsnus
Sounds like RF interference, likely from a voltage transformer stage.
Halogen lamps are infamous for this, unless shielded properly. If you have a portable radio you can likely pinpoint the source by moving the antenna around from several different positions, and triangulate.
A ferrite ring
on the power cable(s) might help.
Speak of halogen lamps. I just got my daytime running lights replaced recently as one of the light burnt out. My car is still under warranty so I took it to bmw. Maybe the guy that replaced the bulb didn't do it properly?
So if I were to switch the original halogen daytime running lights to xenons, it won't make the buzzing sound no more?