Join Date: Sep 2000
Location: Washington, Michigan USA
The tan wire from the sending unit to the gauge comes up through a grommet at the rear of the trunk floor and plugs into a connector in the taillight wiring harness. Disconnect this wire from the harness at the connector, and connect a multimeter (on the ohms setting) between the connector on the tan wire and a good ground. As you gently move the float up and down with a yardstick, the multimeter should read "0" ohms when the float is all the way down (empty), and should read 85-90 ohms with the float all the way up (full). If this is not the case, it's time for a new sending unit.
'69 Z28 Fathom Green