The German Lusso models have no battery (except the Elestart models) and use alternating current at the frame.

For the control of the horn there is a separate rectifier (black box under the left side cover with green/black striped connection cables).
This converts the alternating current explicitly only for the horn into direct current and leads this to the horn switch. This is designed as a so-called normally open contact and closes the circuit when the horn button is pressed.

NOTE: Not usable with the cable harness of the Italian models without horn rectifier.

(US)