Brake lights affecting gas gauge?

#1

After doing more wiring harness stripping, I’ve put almost all the car back together and everything seems to work fine, with the exception of one thing.

Every time I tap the brakes, the gas gauge and temp gauge twitch and read a little differently. From looking at the ETM, I can only see where they connect at the G300 ground. Is there anything else that could cause this strange issue?

ETM

#2

The obvious suggestion is a bad ground somewhere, but no idea where you should look. Depending on how you trimmed wires, you may have something that used to be a ground touching something that used to be hot.

#3

Two grounds to check. The one under the back seat. The massive one under the dash around the clutch. (I’m out of the country so I can’t be more precise)