Toilet Flush repair – Thetford C260

Standard

It’s always the same at the start of a towing season. Some things just don’t make it through the winter. Our first issue is with the electric flush on the Thetford C260 toilet. It doesn’t work.

A quick look around the internet and there’s a few possibilities:

  • Fuse failure
  • Corrosion on the controller circuit board
  • Pump impellor stuck
  • Pump failure

Our first challenge was to find out the model number. It seems the older version is the Thetford 250 and this has it’s own fuse at the back of the cassette enclosure. There should also be evidence of the pump showing as on this older model, the pump is accessed and replaced from the toilet cassette void.

We found no evidence of either of these so concluded we have the later Thetford 260 unit. This should be easier to troubleshoot…

The fuse on our main 12v board serves both the toilet flush and water pump. The water pump is working ok so we probably have power to the toilet. A multi-meter would have been handy but we don’t have one with us.

There’s apparently a technique to tell if the toilet has power – switch on the caravan 12v internal lights and press the flush button. If they dim slightly then that would indicate power is at the control panel. Our 12v LED lights gave no indication whatsoever that power was being drawn. I still suspected though that the unit did have power and it’s just an artefact of 12v LED lights.

I think another way to tell would be to raise the float inside the toilet cassette and see if the red led lights up but I didn’t have any gloves so I gave that a miss and started to dismantle the unit.

Thetford 260 control panel access

Access is under the silver sticker. In this instance it was easily removed with my fingernails and no damage to it whatsoever. I’ll be able to re-use.

Control board removal

Once the cover is removed, the circuit board “pops” off, revealing two screws and access to the pump below.

First impressions are that this compartment is bone dry. I was expecting some condensation and possible damp damage but absolutely none. Everything looks pristine.

Removing the pump

Having disconnected the pump from the control board, the two screws were undone and the pump unit can be teased out.

Toilet flush pump released

Again everything looks in order so time to check the impeller.

Impellor – plastic cog-like structure

It turned out the impellor was frozen and needed releasing with a screwdriver. It was possible to free the mechanism and apply some dry silicon lubricant. Whilst it’s called a dry lubricant, it is a spray and in liquid form!

Success! Now the impellor is free, newly lubricated and the pump spins up. It all goes back together in reverse of the dis-assembly

I can also fit the sticky cover on straight and properly aligned with the recess.

That’s the first item fixed…