What model do you have?
There is no "float" in my grey or black water tanks. On the exterior of the tanks there are wires that run to sensors ~ all you see on the exterior is a screw the wire is fastened with. I check the tightness of the screws every spring after winter storage. You may just have a loose connection.
2012 Fun Finder XT 276 Toy Hauler & Harley Davidson Ultra Classic with Condor wheel chock
2014 Dodge Ram 2500 AT 4X4 Crew Cab 6.4 L Hemi, 373 gears, tow package, Rambox option, Revolver X2 tonneau cover, Equal-I-zer anti-sway hitch.