im trouble shooting my fuel gauge, with the ign on, it goes to full (tanks almost empty)
the sending unit is good, i read the correct ohms up to the front where the plug is under the steering col.
i know one way it will read full, another way it will read empty-like if its missing bat, or missing the grounding from the sending unit, just dont remember which
i know the printed cir has power (dash lights)
hard to see up in there where the plug in is (AC), wanted to test the conn there
could maybe the gauge taken a dump, and is it possible to get to the plug from under the dash

Although not impossible, the gauges rarely have issues. Usually it's the sending units or connections associated with them. What happened when you pulled the tan sender wire connection by the license plate when the key was in the "on" position? It should go PAST FULL on the gauge.

If that works, then stick a wire in the tan wire's connector boot that leads into the trunk, touch it to a bare metal spot, gauge should go to empty.

If these happen, the fuel gauge and wiring between the gauge and the rear of the car is NOT at fault.