[AudiA4B6US]

http://www.nsxjr.com/Audipins.html

 

[AudiA4B6US]

D15 is 12V+ and D12 is ground.

 

[AudiA4B6US]

Which pin connects to the RNS-E from the headlight switch to tell the RNS-E to go from Day mode display and then nite mode display (headlights turned on).

I am getting a loud buzzing sound when I turn my headlights on.

No wire for that, it's a CAN message that tells the RNS-E whether or not the lights are on.