I say again, the Tail Light is not Canbus
http://www.thisoldtractor.com/guzzi007/schematics/2019_V85_TT.gifThe yellow wire is +12 via the ignition switch and Fuse 1
The Green Yellow wire is pulled to Chassis via the ECU
The Dash tells the ECU via Canbus to ground out pin 61 the stop light LEDs
the Tail Light LEDs are grounded via the blue wire.
You should be able to connect other 12 Volt LEDs between Yellow (+) and Green/yellow (-)
Substitute a relay coil then you can add a killowat of extra lights powered from another source.
Its just simple electrickery
There is a lot of Can Bus on this bike, its the twisted black wires between the Dash and ECU ABS terminating on Can L Can H terminals
Not all twisted black wires are Can Bus e.g. the twisted shielded pair to the speed sensor Item (52)