Motorcycle Questions? Ask a Mechanic.
Hi, I’m Louie. Sorry you had to wait awhile but I’ll do my best to help.
Initially, proposed preliminary try (if have not been done) is to hardwire a second ground line from the headlight socket's black/white wire to the Suzuki's body/frame.
Once the ground connection is done, then check the yellow and white wires.
Also consider cleaning the connectors with plastic safe / non-staining CRC 2-26, DeoxIT DN5 or LPS 03116 Contact Cleaner or equivalent.