Thetford C400 control panel problem

[drpeej]

I have a Thetford C400 toilet fitted in my Autosleeper Symbol. Every since I bought it 6 years ago I have had problems with the toilet. Either the toilet flushing button stops working or the flushing pump suddenly starts operating on it's own - often when the motorhome is unoccupied and we return to a whining noise from the pump, an overflowing toilet bowl and an empty flush tank.

It has been back to Autosleepers on two occasions but the problem keeps returning. It is now out of warranty so I have replaced various parts myself. The control panel has been replaced on 3 occasions. The reed switch twice(this shouldn't make any difference I know but Autosleepers told me it was the cause) and I replaced the pump before I came away on our current holiday as well as replacing the IDC plug connectors on the wiring loom.

I am in France at present and it is not working again. The pump burst into spontaneous action this afternoon and I have had to disconnect the control panel yet again. I had replaced the pump and the control panel before we came away because I wanted it to work reliably.

Over the past 3 years I cannot recall a holiday when I have not had to disconnect the control panel and resort to shower flushing.

There must be an answer to this. The wiring is not complex but the control panel seems to be over complex. I suspect the answer is moisture build-up on the control panel.

I have emailed Thetford support but had zero response from them

Have you got any suggestions please as it is really annoying me.

 

[drpeej]

I seem to have posted this in the wrong section but cannot see any way of moving it to the Tech section

(DONE - TJ)

 

[christyler]

do you by any chance have a circuit diagram of the control unit, i have looked on-line but cant find it.

it sounds like, whatever operates the pump (relay or solid state device) is operating intermittently on its own. If its a relay then this can happen when they get old. if its a electronic switch then its more likely that the operation button is worn and faulty.

if you can find the circuit i should be able to tell you more.