Ducati Diavel Workshop Manual page 193

Lights and indicating devices
Fix the front optical applying a torque of 10 Nm ± 10% (Sect. 3 - 3, Frame torque settings) to the nuts (2) with washers
(3).
Reconnect the headlight connectors (A) to the main wiring (refer to the tables of paragraph "Routing of wiring on frame",
Sect. 6 - 1).