fuel gauge?

[C YENSEN]

maybe I got a little ahead of myself, so the gauge isn't working.

All the other gauges work fine, there are four connections and wires on the back of the gauge, the light blue wire and connection on top turns the light on for the gauge, (it works), the connection on the right with the purple wires, is hot when the power is on, the one in the center is the ground, and the connection on the left has a red wire on it.

The one on the left never lights up with the test light. I think it is the one going to the tank. I also replaced the sending unit in the fall.

So I guess my question is

"Should the wire that goes to the tank light up with the test light when the power is on, and should the test light come on at the sending unit?