Grounding the GSS wire out of ECU?

[Jackstand Queen]

My SC conversion was started by someone else, and they didn't change over the dash wiring harness. Hence I don't have a gas select switch under the instrument panel.

The wiring to that switch is complicated by a light inside the switch. But I think if I just ground the GSS wire out of the ECU, that will signal the ECU that I am burning premium.

Or will I fry my ECU and other delicate, rare electronics?

I bet Mr2Tim knows the answer to this one.