How would I troubleshoot the gas guage on a 90'caddilac eldorado with an ohm meter?

I changed the fuel pump pretty sure the float is not stuck down, dont think the guage worked before that, I want to check the wiring before dropping the tank again, I believe it works through changing resistace through the ground? digital dash shows E warning says fuel very low. thanksHow would I troubleshoot the gas guage on a 90'caddilac eldorado with an ohm meter?all gadges work off grond . das is hot an gadde ads grond in moveing restence so check for grond be case lite is on