Hello Frank and
. We are glad to have you join us here and I am sure you will enjoy the website and forums. Good luck, stay safe and keep us posted.
I suspect you are correct in a loose ground. If you cannot reach the top of the tank easily, you might try adding a good ground to the harness wiring ground conductor. When the tank is reading correctly, you should be able to locate that wire with an ohm meter. Once you have found it, add the ground and let us know the results.
Mike, RVIA & RVSA Certified Master RV Technician
Amy, Dr. Assistant - Roxie & Mei Ling, four legs each
2000 Gulf Stream Scenic Cruiser 450 hp & 1330# torque
06 Saturn Vue, 06 Chevy Z71 4x4 & 2014 Corvette Z51 M7