I have a 2005 Winnebago Adventure 38J motorhome. About 4 weeks ago my gray water holding tank level indicator started showing 3/4 full all the time. I have owned this motorhome since October 2019 and the level indicator has always worked correctly. The indicator showed the tank being empty after being dumped , then shows higher levels as the tank filled. I have cleaned the gray water tank out using all the normal techniques (dish washing liquid, strong cleaners, etc, then driving many miles) but nothing has worked and the gray water tank indicator continues to show the tank as being 3/4 full. Then 6 days ago, the black hold tank indicator started showing 3/4 all the time as well.
I will add that when the gray water holding tank get full, the full light (red) come on and when i dump the tank, it goes back to 3/4 full. I have never had the black water holding tank get full so I don't know for sure the full light (red) works.
As I understand it, Winnebago uses proximity switches outside the tank to indicate the level, which means nothing on the inside the tank to get clogged up. There is a calibration technique for the sensor electronics, but i have not tried that yet. I have checked and all the proximity switches on the outside of the tanks are in place and tightly affixed to the tank.
I am new to RVing do i am looking for any help or guidance you are able to provide.
Does anyone else experienced this type of issue previously?
if so, what did it take to correct this?