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 devicesRefitting the starter motor gear
Position the washer (20) and the gear (19) in the pin (21) and take the pin
into contact with the crankcase half.
...
Removal of the camshafts
Unscrew and remove the screws (7) and the o-rings (8) from the cylinder head
covers.
Remove the cylinder head cover (6).
Remove the gaskets (4) and (9).
Repeat the same procedure for the other cylinder head cover. Unscrew the
screws (3) securing the camshaft supports.
Withdra ...
Operations to be carried out by the dealer
List of operations to be performed every 12000 km / year (first
limit reached)
Reading of the error memory with dds on the engine control units,
vehicle and abs
Change the engine oil
Change the engine oil filter
Check and/or adjust valve clearance ( ...