This 914 never had that buzzer but IIRC that's all looped thru seat belts and seat pressure sensors to let you know your seat belt is made. Possibly runs thru the relay under the passenger seat. Note that main ignition rums thru that as well. I pulled the relay and spliced the two large yellow wires to get ignition.

As a matter of interest, did you work out how to disable that terrible buzzer that starts when you open the driver’s door. That is one job I have to do.