Holding tank level sensors bad ?

[RaiderRed]

I have a 2011 Shadow Cruiser, 19 footer. Bought it used. The level sensors in the black tank have never worked right. I tried several brands of sensor cleaner without any improvement. I suspect the original owner didnt drain the tank and the sensors are bad. Looking at them, the wire is easily removed, but I cant see how to remove the sensor itself. It is about one inch round and appears to be held in place by some kind of sealant. Does all the sealant around the edges have to be removed to get it out? Is the sensor only held in by the sealant? If I get the top 2 out, can they be cleaned or do they have to usually be replaced. Anybody worked on this problem before that can help would be appreciated.

 

[RaiderRed]

I just found on another site info on how the sensors work. If what I read is correct, the screw that holds the wire actually is the sensor. The screw is very short and doesnt look dirty to me, but I guess I was expecting more to the sensor than just a screw. Is this how they work? Liquid contact on the screw causes the circuit to show the reading on the guage?

 

[M Wilkie]

I posted this recently. We bought our FF189FBR used in January. The black tank sensor always read 2/3 full, no matter how many times we emptied it. We had bought this in January but forgot we had it. We used it for the first time this last trip at a State Park dump site. He made sure to fill the black tank very full. It took under under 10 minutes to do the entire flush and it removed more sediment than just dumping did. The sensor works great now. Problem solved.
Camco 39062 Dual Flush Pro Holding Tank Rinser with Gate Valve https://www.amazon.com/dp/B000BUQOAE/ref=cm_sw_r_cp_api_7p1KxbH3XZ8R7

 

[Dakota 1120]

I posted this recently. We bought our FF189FBR used in January. The black tank sensor always read 2/3 full, no matter how many times we emptied it. We had bought this in January but forgot we had it. We used it for the first time this last trip at a State Park dump site. He made sure to fill the black tank very full. It took under under 10 minutes to do the entire flush and it removed more sediment than just dumping did. The sensor works great now. Problem solved.
Camco 39062 Dual Flush Pro Holding Tank Rinser with Gate Valve https://www.amazon.com/dp/B000BUQOAE/ref=cm_sw_r_cp_api_7p1KxbH3XZ8R7

My unit has a built in "black tank flush" which seem to eliminate the need for the sewer drain adapter to blow water back up into the tank.

 

[Dakota 1120]

Here are some methods to get those black/grey water tank sensors functioning properly.

Here is a good explaination and a outfit that sells replacements that are touted to be better than factory sensors ... but a tad on the spendy side.

RV Holding Tank Sensors - Get accurate grey and black holding tank monitor readings

 

[M Wilkie]

Yes. Newer units have those. Ours doesn't but this works well.