It should not read full at all are's shows empty all the time. If one is showing full that is the one that you are using. If it is showing full all the time you may have something stuck on the sensors really common problem. Or you have a problem with the sensor. They are not the most accurate to start with we are used to it and jest know when to dump.
Bob & Carol Washington St
2017 HC HM352RL 2018 Dodge 3500 laramie CC LB 4x4
Curt Q25 with puck system, Factory air bags