Diagnostic port for level sender, which one?

[CactusS4]

I've been lagging and driving my car without the level sender plugged in, since day one the system would not recognize it. I've gotten off my arse now and want to check the voltage, and it appears that the diagnostic ports should allow me to get the required information to know if this is a defective sender or something else.

So which test port, I can check it with my voltage tester

Thanks