Digital read out and gauges not working - 2001 Chevrolet Silverado 1500

Instruments are generally supplied with power from a common source and if the other dashboard lights and gauges work it is a fair assumption for the time being, loss of power to the circuit isn't the problem.

Most fuel gauge problems are caused by either the fuel tank ground being lost or the rheostat inside the tank sender failing.

In the traditional fuel gauge circuit when a bimetal, moving coil or moving iron gauge is used, the circuit can be tested simply by shorting the wire to the gauge unit to a good ground when the gauge would read full, proving the gauge and wiring is ok.

It is best to be aware other types of gauge might be used and modern digital vehicles might have to be treated differently - instead of being grounded a sensor substitute might be needed or simply test the tank unit with an ohm meter.

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for nothing on the dash to work ,it indicates that a ground wire is missing, broken or the ground point is rusted
Could be the BCM unit so run the fault codes as well

Bad sending unit, bad ground, bad gauge, I have seen sending unit go bad they will work part way.

Unfortunately, you cannot. Before replacement you needed to check gauge by grounding wire to block to see if gauge pegs, if the gauge does not move problem is in the gauge. I have worked on so many different vehicles, so my thought might be on a non digital type gauge not a digital. If digital gauge disregard this test.

The values differ in all types of cars. Older cars peg out at 90 ohms. Newer cars range between 0 and about 400 ohms. Dis-connect the connector at the sender. Ground the sender wire and the gage should read empty. un ground and it should read full. They use a ceramic resistor in the tank that usually go bad.

check the printed circuit board on the dash panel

maybe pixels gone bad check that.

Sounds like your sending unit could be bad.

The sending unit in gas tank is broken - hence the wrong readings of how much gas is in the tank. Replace unit.