Ground (GND) to the lamps:

For the rear lamps the GND is not any issue. The indicators are mounted direct into the frame.

For the front indicators it’s more difficult. On my GT750A model the head light house is all metal and clamp GND direct to the headlamp bracket. On my GT380J it’s different. To make a proper grounding I solder wires to copper spacers and they were both connected to the GND wires inside the head light.

Wires from the spacers connected to GND.

Green wire (right indicator lamp) Black wire ( left indicator lamp)

All indicators worked fine, + the instrument lamp as well 🙂

Looks like all of the electronics are working fine without any smoke 🙂