Check the harness connector that's under the tank,
While you're down there.....and to narrow it down a bit..........
Parallell to the multiconnector for the switch assy it's a single connector (brown/white wire).........
Yes, it's for the cancel switch............while the flashers is on, short this wire to ground using another
piece of wire.
If the flasher stops, the problem is most likely in the switch, but could also be in the single connector
or the wiring between.
If the flasher don't stop, the problem is most likely in the relay, but could also be in the relay socket or
the wiring between the socket and the single connector.