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 devicesRemoving the electrical components support
Remove the following elements located inside the electrical components
support:
The battery fixing bracket (4) and the battery (14) as specified under
section 6 - 2, battery;
The voltage regulator (3) as specified under section 6 -
2,rectifier-regulator;
The solenoid starter (18) ...
Hands free
Hands free
Special screw
Plug
Electric fuel plug
Button
Spring
Frame
Elastic pin
Spare parts catalogue
Diavel abs handlebar and controls
Diavel carbon
abs
handlebar and controls
Important
Bold reference numbers in this section identify parts not shown in the
figures a ...
Hydraulic clutch control
Special screw
Sealing washer
Clutch master cylinder
Clutch hydraulic pipe (metal braid)
Screw
Spare stand
Washer
Microswitch
Pin
Bleed valve
Screw
Roller
O-ring
Clutch control rod
Clutch lever
Dust cap
Bleed valve
Special screw
Sealing washer
Boot
Plug
...