Gauges

OK, look, I thought maybe my post above might inspire some research

Negating the internal IVR, and just describing the "functional path" Here is how all gauges work except the ammeter

Power comes from ignition switch..........to the limiter/ regulator......and feeds to one post of the gauge, through the gauge...........to the sender wire.......back to the tank.......to the sender.........through the sender to ground

There are several pitfalls there for trouble, "in general."

Bad IVR, bad gauge, bad connections at the gauge studs, problems with the cluster PC board traces and connections to the harness connector pins at the PC board

Bad connection in the sender wire. There are terminations at the PC board connector........through the left kick panel connector, the terminal right at the tank

The sender itself can obviously be bad/ intermittent

So how do you test it?

Refer to my post above, the photo of the factory test "rig." NOTICE THE RESISTANCE values. You disconnect the sender, and substitute resistors of know value (or that you can measure with a multimeter) and those resistor values should give the readings at the gauge as noted

It DOES NOT MATTER if it's fuel, oil or temp gauge. They all work the same