Hi Hutchie,
If Cain's suggestion about the O2 sensor and SV were spot on, you would be saying that you had a yellow FI fuel injection light hard up and a code number if the diagnostic plug was connected with the short across the right terminals as referred in Gritty's post with the toggle switch.
I think the answer is a disturbed wiring harness going up to or behind the speedo unit.
From Gritty's Post 18:
" If CHEC is indicated, the LCD does not indicate the trouble code. (like C34 or something)
It is necessary to check the wiring harness between ECM and combination meter couplers" . Combination meter couplers means speedo head unit in Suzuki speak to me.
The speedo head unit has it's own electronics and power supply and the 'couplers' is the wiring harness, plug and sockets.
The ECU has by itself enough to make the bike run, and the speedo head is the information interface for us, Humans.
Rob.