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 devicesRemoval 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).
...
On-board computers and the can line
The following on-board computers make up the electrical system of the diavel
and are connected with each other via the
can line (or network):
Master dashboard
Slave dashboard
Hands free (facilitated keyless start system)
Ecu (engine control unit)
Bbs (black box system or central elect ...
Vehicle speed indicator
This function displays vehicle speed (km/h or mph depending on the set
measurement system).
The dashboard receives information about the actual speed and displays the
number increased by 5%.
Maximum speed displayed is 299 km/h (186 mph).
Over 299 km/h (186 mph) the display will show a s ...