The negative cable, which is normally connected to the negative pole of the battery, is fastened to the crankcase. From here, the cable branches off and splits up within the electrical system to carry the ground connection to the different elements in the system.

The image shows the ground connection on left side of the engine crankcase.
The battery charging circuit and power distribution
Electrical power for lighting and signalling devicesWarranty
In your own interest, and in order to guarantee product
reliability, you are strongly advised to refer to a ducati dealer
or authorised service centre for servicing that requires any
particular technical expertise.
Our highly skilled staff have the tools required to perform any
servicing job ...
Indicator trip time - trip time
This function shows the vehicle trip time.
The calculation is made considering the time travelled since the last trip 1
reset. When trip 1 is reset, the value is set to
zero.
The active phase calculation occurs when the engine is running and the vehicle
is stopped (when the vehicle is not ...
Removal of the fuel tank filler cap
Remove tank covers (sect. 5 - 2, Removal of the fuel tank fairings).
Remove hoses (8) and (15) from the filler cap assembly (10).
Open the filler cap.
Unscrew the outer screws (17) securing the ring nut to the filler cap recess.
Remove the filler cap assembly (10).
...