Fuel gauge reads empty all the time

Diagram I have for the cluster says #2 pin fused B+, #6 pin panel lamps driver, #9 pin CCD BUS -, #10 pin CCD BUS +, #11 pin fused ignition switch output. Almost ready to order BCM and drop tank back down to check float. Will check BCM pin 46 first and get back with you on that. More gray hairs!

At wits end. I applied 2.5 volts directly to the cluster.. Pins 9 and 10. Positive and negative and the gauge didn't move. So I thought if it is bad can't hurt to apply same voltage directly to the gauge. Jogging between the four pins on back of gauge. Still nothing? I have ordered a used one that is warranted to work and for 6 months, . But still unsure of what is wrong. Help!