Thetford C402 pump will not stop running !

Mar 17, 2012
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Hi to all HELP,
My Thetford C402 will not stop running , I realise there is a PCB behind the switch which operates the flush, also there is a reed switch inside the waste tank compartment which houses a 3amp fuse.
On the PCB there is power in and power to the pump all the time obviously there should be power in and no out put until I press the flush button .
Has anybody had anything like this and could someone explain how the PCB and reed switch work ??
Thanks
 
Nov 11, 2009
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Fatboy said:
Hi to all HELP,
My Thetford C402 will not stop running , I realise there is a PCB behind the switch which operates the flush, also there is a reed switch inside the waste tank compartment which houses a 3amp fuse.
On the PCB there is power in and power to the pump all the time obviously there should be power in and no out put until I press the flush button .
Has anybody had anything like this and could someone explain how the PCB and reed switch work ??
Thanks

There is some useful support info on Thetford website. I think that there’s even some graphical videos on YouTube. Mine isn’t exactly the same model as yours but it too went into continuous running. I was going to install a switch to control the flush. But in the end I removed the push button cover on top and removed the pcb. Sprayed it with contact cleaner and gently cleaned the connectors. Then reassembled and sprayed with electrical lacquer. Worked okay ever since.
 
Jan 19, 2002
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Not sure if it helps but there is an exploded diagram on the thetford website
file:///C:/Users/rjmil/AppData/Local/Packages/Microsoft.MicrosoftEdge_8wekyb3d8bbwe/TempState/Downloads/Spare%20part%20list%20C400%20(1).pdf
and guides to download here
https://www.thetford-europe.com/product/c400/
also links to spare parts.
 
Mar 17, 2012
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Thanks for that , I have already cleaned the board with contact cleaner to no avail also have gently cleaned the sockets with all the wires in .. still not stop ☹️
 
Nov 16, 2015
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Depending if on how long away, Take our the power fuse and have a watering can handy until a new pcb, or repaired .
 

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