I have triton 430 which I bought new just under two years ago. On my first trip of the year the flush on my 402c thetford toilet just didn’t work. Nothing. No sound, no flush. Seemingly dead. Came home and researched and looked at previous threads. I’ve now taken out fuse and that’s ok. Taken out the pump and tested that and that’s working ok so my question is , does that mean it’s the circuit board that needs replacing or could it be something else? Thanks in anticipation.

Common problems with the Thetford toilet after a long winter of inactivity include jammed pump, corroded connections to the pcb and a corroded fuseholder in the waste tank area.

Pump is ok, but when you checked the fuse did the blades look nice and shiny or were they dull and perhaps corroded?

I doubt very much the pcb has an electronic type fault after just sitting around doing nothing.

If I were you I'd put a new fuse in, reconnect the pump, clean up the PCB connector pins and see if that's fixed it.

Thanks for your response. The pump is ok. I just connected to external water connector and it worked fine. Fuse is new and old one looked fine without corrosion. I tried bypassing the pcb by connecting red live lead from Eriba to brown wire from pump and black to blue which if everything was working ok should , I presume, have resulted in pump working. Other odd thing is that when I place multimeter just on the leads going to pump there was a reading but not when the wires were joined together. Frustrating not knowing what if anything needs replacing or sorting.

YouTube repair video for C250

From what you've written it seems you might not have 12V to the pcb - check with your meter to the red and black wires on the pcb connector.

If ok, test for 12V on the pcb connector pins that go to the pump and press the flush switch - you'll probably need 3 hands to do this!

I'm not sure what model Thetford you have, some have a pump relay to the rear of the waste compartment.

Hi
I just checked with my multimeter and there is electricity coming through to the pcb. What I can’t understand is that when I connect two different pumps(which I know work) direct to those wires nothing is happening. Is there some mechanism whereby the pumps need something other than direct electrical flow in order to work. I’m baffled and in a fit of frustration I put everything back together filled up the tank and in a show of hope over logic pressed the flush button and of course nothing happened. Looks like I’ll be manually squirting water down the pan until I can get someone to look at it. Im now going to to find a secluded spot and scream.

Without the model of your Thetford toilet I can't help any further.

In the first thread the OP says it's a Thetford 402c

I didn't register the model number quoted in the original post - must be going blind in my old age!

Anyway, that model is fairly straightforward with no relays or similar complications.

Try measuring the 12V at the pcb with the pump connected and press the flush switch. If it drops appreciably then there must be a bad connection in the 12V feed, either in the red or the black wire.

There will be a connector between the van's wiring (blue and brown coloured) to Thetford's red and black wires. This is usually found in the cassette compartment, front right hand side (by the door).

Another possible bad connection culprit is to the fuseholder, so worth checking there aswell.

Good luck!

Thanks I will check out those things and hope for the best.