if your sure the dump valves and tank gauges are correct, only other possibility is toilet is emptying to gray tank. Do you use a clear adaptor on your dump hose so you can see what is coming out of each tank?
The Tecma has it's own 'full tank' sensors separate from the 'house' gauges.
It is simply stuck onto the side of the tank with double sided tape.
The factory apparently has stuck the sensor on the side of the wrong tank.
That makes since and thankfully it was a easy fix. Do you have issues with the Tecma not filling after a flush. I'm on my second toilet and third control bad and it fails to hold water after a flush half the time.
Phil, Have not actually fixed it yet, just figured out what was going on.
Other than it won't flush when the 'gray' water tank is full, it seems to work great.
Or so Nickie says, since that is her bathroom.
Hopefully you can get to the sensor pad and just switch it to the black tank.
I get the bathroom thing I use the 'good" bathroom for a shower only.
I can't imagine what is wrong with that Tecma toilet. It's been that way since we bought the MH. I will call Thetford and see what they say.