Thetford 'Full' Light not working ?

[JohnnyV]

Hi,
Can anyone help ?
I have a Thetford C250 fitted in a Lunar Delta (09) - the little red light on the top that tells you it needs emptying has stopped working - I have checked the fuse (OK - anyway the electric flush still works), thought it might be the float in the cassette not lifting (it is), and finally I followed some earlier advice and lifted the sticky backed cover and accessed the printed circuit board (all in place) - I can't see what should actually light up on the board ?
I am guessing this is going to mean a trip in to the dealer under warranty unless some kind soul can point out something obvious ?
As you can actually see into the cassette, we will still be able to use it and empty when it gets towards the top, if it does have to go to a dealer I will probably wait until its next due for service.
A trivial thing but I hate things that don't work as they should !
Thanks in advance
Jon

 

[GeorgeandAde]

Hi Jon.
I may be wrong, but im pretty sure that our light is powered by 2 small batteries which are in the outside cassette compartment.
Hope this helps.
Adrian

 

[mullsy1]

Same here.3 xAAA batts on mine in the cassette compartment

 

[SirRogerFFS]

Hi Just having the same problem on our 2010 Sterling.
Have found the secret here and this is it , clean out casette thoroughly including the float you can see as this also lifts a magnet within the casette.
Sounds stupid but put at least two litres of water into the casette or more ( suggested ) and use any toilet roll you like except good ones and you should bo OK we are using Andrex white at the moment and works well .
It is suggested you use Thetfors own .
I hope this helps

 

[SirRogerFFS]

Just as an add on check at the back of your castte housing right hand side and see if there is a small electical contact as there are no batteries in our housing that are visible ,as I said when the float lifts it also lifts a magnet and the magnet makes a contact somehow thro cassete.
You could always try filling casette with just water and test it this way.If light comes then change you toilet roll or as I said add more water
Sir Roger

 

[JohnnyV]

Thank you for the suggestions - never thought of it having a battery anywhere - would have thought it ran off the 12v van system.
Have tried filling it with water - float rises fine but still no light
Will have another look this weekend - didn't think of a magnet being involved, in fact I couldn't work out how it sensed it was full ! I suppose the magnet could be 'stuck' - either that or the sensor is not being activated, or something as simple as the neon being busted.
Jon

 

[chrisn7]

Not sure about the C250, but the C200 definitely uses a magnet to activate the full light. What usually happens is that vigorous shaking when emptying dislodges the magnet, which is then lost. If you are lucky you will hear it rattling around the tank. When replacing the magent, use the smallest tie wrap you can find around the plastic clip that is supposed to retain the magnet-this gives a permanet solution. You wil not enjoy re-fitting it however....

 

[waffler]

Some vans don't have separate batteries but run off the leisure battery. Have the dealer check the LED. There is a history of these failing. If anyone has to pay for this themselves the 3 volt led is cheaper. (Apparently cheaper to use 3 v and buy batteries.) The thetford fridge has had some led failures as well.

 

[Cal1]

You need to check if the problem is in the removable cassette or in the system itself.
To see if the problem is in the cassette, remove it from its housing.
Then get a small magnet, and hold it against the small reed switch in the now empty housing (the one with the wires on it near the fuse), and have someone inside to see if the 'full' light comes on. If it does, then the problem is inside the cassette. It uses a small float, that has a permanent magnet attached. As someone mentioned above, you will need to see that the float lever is moving freely, and if necessary replace the magnet.
(The reed switch is comprised of metal contacts, that come together when a magnet comes near them)

 

[JohnnyV]

Cal,
Thank you for the tip - I am fetching the van out of storage on Saturday and will try your magnet idea !
I haven't heard the cassette magnet rattling around in the cassette - but the fault happened when my Daughter had borrowed the van - is it possible it was 'tipped away' when the cassette was emptied?
Much appreciate all the help
Regards
Jon

 

[mealsonwheels]

The warning light has stopped coming on when our 2yr oldThetford toilet is nearing full too, so we're interested to read these comments and suggestions.

 

[Clive-Cardiff]

Remove the cassette and have a look at the left hand side of the inside space. There is a little reed switch attached to the side. Pass a magnet in close to the switch while someone is watching the light in the van. If the light comes on the fault is inside the cassette. No light means the fault is in the circuit or the led.
A fridge magnet should be strong enough to carry out the test.

Sorry just read the rest of the posts to see that this procedure has already been suggested

 

[JohnnyV]

Well I have tried the magnet 'test' and no light so I guess that means it is someting to do with the reed switch or circuit board - I think this will be a warranty job on the next service.
Thanks again for all the helpful suggestions.

 

[chrisn7]

Yes its almost certain it was discharged along with the cassette contents! When it happened to mine, I initially thought my young daughter had dropped some toy in there-probably got a few funny looks peering into the cassette! The magnet is very small, say the diameter of a pencil, but its heavy enough to escape its plastic clip when shaken.

 

[vauxhall2]

mine stopped working and i found the battery holder inside the compartment opening for the tank was corroded to excess.i removed it and soaked it in boiling water to remove any residue.used a nail file board to clean the contacts back to bear metal.sprayed with WD40 and fitted two new batteries and its fine now.

 

[pmitchell]

i have read all your comments and mine is the same light does not come on.so thinking either led light or the battery, but i am struggling to find where the 2 batterys are kept.found the fuse and the reed and i am going to test them with a fridge magnet now but cannot find where the baterrys are kept,need help

 

[xtrailman]

I must be very sad, i think i better start my winter project early this year.
Having just read all the posts relating to a toilet full light, i really do need help?

But having said that i have learnt something new, wasn't aware batteries were sometimes used.
This can only be to save the cost of cabling etc.
We always use the "look in the pot" method, but ironically our full light still works.
But i do recall the empting instructions advise against inverting the cassette while emptying to prevent damage to the mechanism.
I do anyway and as i have already said my light still works?

Hope you have remember to switch the 12v system on while testing?