Thetford toilet flush… not working…

If your C250 Thetford toilet stops flushing there could be several causes…

  1. The pump has failed or cracked during a freeze over winter.
  2. It has “jammed”
  3. The “fuse” has gone or the Fuse Contacts have corroded (inside the toilet compartment at the rear).
  4. The Control panel has corroded contacts
  5. The Flush button is faulty.

To remove the pump, you have to get underneath inside the compartment – follow the water pipes – remove the pipe(s) and the pump should come down…. visually check for damage, turn the impellow using a (very) thin screwdriver and try it again.

There is a “blade” fuse (and a spare) at the rear of the toilet compartment – the contacts can corrode – clean these with WD40.

Inside the caravan – the top of the toilet has a “flush” FLUSH button (its fitted”flush” you see!). To get to the switch – use a Stanley knife and carefully prise the plastic membrane off (don’t cut it!). Try not to touch the sticky side – you will want to refit it afterwards.

Behind this membrane is a circuit board. – you may need to ease it off it’s plastic retaining clips to remove it.

The edge connector where the cable fits is prone to corrosion. In fact, the whole board is!!!! Try cleaning the edge connector by scraping and WD40.

In my case my Switch had gone faulty – I tried to find a replacement – it has to be EXACTLY the correct height – I found one close – but slightly too high… now I have a “Spare board” which works if I insert a piece of plastic under the PCB to act as a “spring” !!!!

So I had to fit a new board. Before I fitted it, I gave it a couple of coats of Spray Acrylic Lacquer to protect the board from damp in future.

Refit the board and then try to refit the membrane. If the membrane will not seat properly – either buy a new one from Ebay for around £12 or do what I did – I glued it down using Silicon Sealant!

If your “Toilet Full” LED doesn’t light – you *may* have lost your float in the soil tank (it happened to me about 30 years ago) or most likely its corrosion on the REED switch sensor board or the REED is faulty. Either remove the corrosion, or Replace the board for lots of money – but cheaper on Ebay than a dealer!

Inside compartment showing fuse holder and level sensor board
Membrane removed, showing panel underneath. Use a small screwdriver to lever this out to access/release the PCB.
The Expensive Board. If you do “Lacquer” it.. make sure you mask off the edge connectors!

If your pump has failed you can either fit a replacement Thetford pump – or fit a cheaper substitute – check the fittings first! You may as well fit a cheaper one – it doesn’t work very hard, but they do crack if they freeze up.

TIP: Every winter, I flush my toilet flush through with Car Anti-Freeze… It’s not possible to get all the water out of the system without stripping it, so why not put a liquid in there that will not freeze up? It works for me!