Since buying my present motor home I have had trouble with the tank guages, the black water shows 3/4 full when empty and the grey water shows 1/4 full when empty. I returned the motor home to the dealer and they worked on them and said they were repaired but when I took it out the next time , they still were not working. I decided to try and repair myself and removed the screws in the black water tank to see which one would make a difference. When I removed the highest screw in the Black Water tank and cleaned the screw, connection and the wire end , it worked for a short time. Then problem came back. what ever is causing the problem it affects both tanks, black and grey. for when it was working right both tanks showed empty the way they should. Is there some method for me to check for either broken wire or maybe bad ground. I am not sure how these things work. Maybe someone has had the same problem and can tell me how to go about checking them.
Probably you have something on the sensors inside. They are notorious for getting tissue paper or anything else in the tank on them and showing a reading when nothing is there.
When mine does that I use one of those magic wands that spray water under pressure through the toilet until they are clean. This is a very common problem. Even soap suds from the kitchen sink will remain on the sensors for quite a while sometimes.
You may not have an electrical problem at all but just dirty sensors??
Also after I dump the black water I fill the tank again with clean water and hope that will help
‘flush’ out the tanks well enough for the sensors to work properly. Invariably they will clog again however. It seems to be a never ending problem.
OK, I have the hydro flush, great thing but the bottom line is that I can never seem to get the blank tank empty. ,I thought it was the level of the rig, but dropped the tounge all the way to grade and there is still 1/3 full. I can visual the level through the john. (Black tank is in the rear with outlet facing forward in center) I tried to lower mirror through john opening to see discharge but no luck. Camping is no fun when you have 30% full on the word GO. Any suggestions???