Hey Joe - Like the 1500 GW - the 1200 turn signal and 4 way flashers are actually divided into two (almost) identical circuits and except for the Auto-Canx Control Unit - troubleshooting is pretty straight forward.
There are 2 interchangeable Flasher Relays. 1 operates the Turn Signals and 1 for the 4 way flashers. The two relays are mounted across from each other near the yoke below the ignition unit. The false tank must be removed for access.
1 Have the turn signals ever worked properly ? Are the bulbs the original filament style - or have you replaced them with the newer LED's.
2 Do both Left and Right (Front/Rear) turn signal lights come on - just don't flash ?
3 Do the 4 way flashers work ?
4 From memory (?) I think there are two fuses to check - fuse 5 (15 amp) = turn signal relay power, and an (In-Line) fuse below the fairing pocket insert = 4 way flasher relay power.
5 The handle bar - Turn Signal Switch internal contacts can be the source of the problem. Carefully disassemble the switch contacts and clean. Watch for the small parts to try and escape.
6 Inspect both flasher relay socket connections and/or relay pins for corrosion. Swap the two flasher relays - Retest the Turn Signals.
If you have to chase down a wiring or ground problem you'll need a schematic for some color codes and additional component locations.
Keep Us Posted - Michael