[dbmotors]

Two comments I can add. One, I have looked at my black tank (actually, all three of my tanks) and the sensors are located in odd areas. For example, the "full" sensor is located probably 3" from the top of the tanks. I too was having my black tank read full within a very quick time, but in reality, the tank is not full.

Second, my black tank frequently reads full even after I empty it. As was stated, if something is touching the sensor (like toilet paper), it will trigger that light. I no longer put much faith in my guages...