How do I test my instrument cluster?
Do it right. You need to read this thread........
Printed circuit pins repair
You need some resistors or a variable resistor such as a fuel sender that you can adjust to different resistance to act as a sender
You need to use a battery NOT a charger, and figure out how to substitute resistances shown in the photo for each sender. All 2 or 3 gauges should read the same with the same resistance, they are the same gauge movement.