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Thetford Tecma Silence Plus Problems

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#1 monacomadness



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Posted 02 June 2013 - 03:13 AM

Help anyone!!!!


I have a Thetford Tecma Silence Plus RV toilet. Recently the tank full red light stays on all the time. Would not override flush. It started when emptied tanks the green light would not be on but yellow 1/2 full light would be on.


This went on for a month or so but on our trip to Montana the red light came on and nothing works! I spoke with Thetford and was told I would need to replace my double wall switch. Got it and did not fix problem. Again Thetford told me to get controller, I did and problem is the same except that now I can override a flush. Still red! Took RV to Britz RV & Marine in Billings. Over $300 later, they removed the red sensor and could flush toilet but would not know when tank is full.


Not a long term solution. Spoke with Thetford again and they said to replace sensors. Just got them and installed to no avail. Still seeing RED!


Can anyone PLEASE help me????? I've got over $1000 into a stupid toilet! Am I overlooking something.


Seems Thetford is only playing a guessing game with me. HELP!!!!

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#2 DickandLois


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Posted 02 June 2013 - 06:36 AM

Monacomadness, Welcome to FMCA.


Sounds like everything has been replaced. So what it sounds like, is a wiring issue as you can get the unit to work if the sensor connection(s) are disconnected.


To me that would mean the sensor circuit is reading or sensing something other then the fluid level(s).


Check all the wires running between the tank sensors and the control board for chaffed wires contacting metal between the tank and the board.

You might be able to see if someone knows what the resistance reading(s) should be for the sensors. Measure the reading you get at the connector terminal for all of them.


Also, check for proper grounds in the circuits, one loose or corroded connection can do you in. You did post that it went from green, then to yellow and then to red with no liquid or very little in the tank. Keep thinking Ground, Ground and Ground.


The control board is reading, or I should say sensing a voltage level that is there only because of the lack of a good ground.


So many times the shops just replace parts until the problem goes away and never know what the real issue was.


Good luck and keep us posted.



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#3 MichaelS



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Posted 12 June 2013 - 09:23 AM

I know this sounds obvious, but have you given the tank a real good flushing. I am fortunate and have a spray inside both tanks so can give a real rinse out fill with fresh water dump and spray again. I see that my amber light comes on prematurely or indeed I have no green if I do not flush through every time I dump?


2008 CC Allure

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Michael Slater
Falmouth UK
2008 CC Allure 470

#4 petenancy



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Posted 23 October 2013 - 10:28 AM

I have a Monaco with a similar problem. In my case the light will oscillate between red & yellow but override still works. The sensors are placed where they cannot be seen. I'm checking for a loose ground wire but haven't found anything yet. The yellow light will stay on for days at a time but when I dump the oscillating returns.


If I can figure this out I'll let you know.



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