Thetford toilet warning light query!

Jun 15, 2018
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Hi all.
My caravan has a Thetford C200 CW toilet.
I gather it should show a green light,then it changes to red nearing to getting full.
In the cassette compartment,i have found the battery holder and wires going off up,to which i assume goes to the led.Also wires going to what looks like a oblong small block.

I cant see any sensor conection what so ever on the cassette that side.Any idea how i can get this working,as im a bit lost as to whats adrift.
Many thanks
Pierre.
 
Apr 19, 2017
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It's a reed switch actuated by a magnet on the float arm within the cassette. The float is a notorious cause of trouble on all models,even the old ones with a mechanical display. It is far more reliable to simply look down the hole! :)
 
Jun 15, 2018
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Thats what i had been doing..lol
So not worth the hassle of trying to get it going then.
I will take your advice and look down the hole..lol
 
Nov 11, 2009
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Can’t recall mine ever showing green but the red does work. However it will go red at the worse possible time last thing at night when it’s blowing a hooley. By then it’s got pretty heavy too. So as said above just look down the bowl, or you can listen to the “stream” :)
 
Mar 8, 2017
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Mine only ever shows red, and then only if the float switch hasn't jammed, so the advice to look down the hole is good.

For memory (rather shaky at the best of times) when the red light illuminates there is supposed to be room for another litre. So unless you have had a curry :sick: you should be OK until morning.
 
Oct 8, 2006
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Its a good idea to clean the waste container periodically - perhaps typically at the end of each season. Wear good quality waterproof gloves (nitrile are as good as any) as there will by definition be waste products around.
To clean it remove it, empty it if necessary, and place it flat on the ground. Remove the slide cover over the trap completely. Then get a piece of 3x2 timber or similar about 15-18in long, place it diagonally between the slide runners and twist anitclockwise. When the lid has rotated about 30 degrees (as far as it will go) lift the lid out - you may need to use some sort of lever as they do stick a bit. The trap assembly can then be cleaned independently - and believe me it is a bit unpleasant. Take car to ensure the air valves both work properly; there is one under the Thetford badge (lifts out) on the top near the handle and a second under the pressure release button that you press when emptying the container.
The important bit is the level float which will be on the side wall of the container such that it aligns with the external reed switch - some are at the back, some on the side. Make sure the float moves easily and does not have paper debris stuck behind it. Even take it out, clean it and the mount, and smear some olive oil on the mount before refitting.
When you have cleaned the trap assembly smear the lid seal and the trap seals inside and out with olive oil (as recommended by Thetford) and then reassemble.
 
Jun 17, 2011
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There is only a red light. If someone has shaken the cassette vigorously the float may be adrift. This is quite difficult to refix but there will be instructions on Thetford website. Try looking on YouTube also. Most probably the float is stuck down with bog paper, Thetford recommend soluble paper to prevent this. I have heard of some leds failures. Since being caught out, like Otherclive, I empty ours every day usually when the weather is reasonable. (We never use site facilities hence daily.)
 
Jun 11, 2012
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I am at the end of my patients with the c250 What with the micro switch on the board of the flush tank and the reed switch in the cassette housing. I have had 4 new boards housing the micro switch and now mine has blown the circuit board for the reed switch for the full light. My service engineer said when the next board wants a micro switch we ditch it and just a nice neat switch in to flush the loo. This Thetford system must be the worst thing ever designed. I have heard they have changed it in newer vans ..
Sir Roger
 
Aug 7, 2017
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Seems like a common issue with the cassettes floats, I filled mine up yesterday to see wether the red light would come on but to no avail. My float in the cassette seems to get stuck coming up to where it should be, but i'm not bothered because if it ever gets that full then someone needs to go to the doctors if they are using the toilet that much lol..
 
Nov 11, 2009
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SirRogerFFS said:
I am at the end of my patients with the c250 What with the micro switch on the board of the flush tank and the reed switch in the cassette housing. I have had 4 new boards housing the micro switch and now mine has blown the circuit board for the reed switch for the full light. My service engineer said when the next board wants a micro switch we ditch it and just a nice neat switch in to flush the loo. This Thetford system must be the worst thing ever designed. I have heard they have changed it in newer vans ..
Sir Roger

I don’t seem to have had the problems that you and others have although the pump pcb has had to be “seen to” when the contacts became corroded. But if I should have issues then I too will be fitting a flush switch to power the pump and rarely do we need a red light to tell us the tank is getting full. We both have excellent eye sight and finely tuned hearing.
 
Nov 11, 2009
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Craigyoung said:
Dustydog said:
And how about your nostrils Clive :p

Haha
that's just what I was thinking too !! :sick:

Ah well clever clogs my sense of smell went some years ago when I was involved in firefighting training and exposure to smoke and artificial smoke seemed to kill it. Some members of my family take advantage of it by blaming me for their “windfalls”
 
Nov 11, 2009
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Craigyoung said:
Ooops . Sorry . :blush:

No need for any “sorry” at times it has its plus points. Anyway sat in flat in Leicester watching footie and since place isn’t exactly pristine I’m quite content eating pot noodle and drinking coke and am I glad Dusty didn’t mention sense of taste or touch :)
 
Nov 6, 2006
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Its very easy to lose the little magnet in the float, as its only clipped in by the plastic. Vigorous shaking to dislodge contents results in the magnet getting thrown out, unless you happen to hear it ratting around as I did once. Fixed it permanently in place with a fine tie wrap.
 
Nov 6, 2006
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The connections to the C250 pcb clip directly to the board, but the copper tracks are very thin and corrode away to nothing. My solution was to follow the track a little, clean it and solder the wiring directly, eliminating 2 potential failure points.
At the fuse, the terminals to this are the most complicated devised by man and incapable of being cleaned of corrosion. I soldered 2 new ones in.
Finally, the pcb and fuse are mounted on a plastic tower and vulnerable to 'splashes', so I covered the tower with an thin inverted plastic bag.
At the float take your (old) toothbrush and clean around to dislodge any wayward paper as there's not much clearance, and all should be well..
 
Jun 11, 2012
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Being less technical why not just do away with stupid idea anyway and just peep down the hole you will know when ts full.I have just done away with reed switch idea its been an absolute pain in the arse. What with the reed switch and the micro switch and the board that houses the PCB worst idea ever .The board on the top of C250 has been our problem our van is 8 years old and its on its 4th pcb. next time it will be fitted with a small switch to flush it . Thats my moan over and my cheap way out .
Regards Sir Roger
 
Nov 11, 2009
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chrisn7 said:
The connections to the C250 pcb clip directly to the board, but the copper tracks are very thin and corrode away to nothing. My solution was to follow the track a little, clean it and solder the wiring directly, eliminating 2 potential failure points.
At the fuse, the terminals to this are the most complicated devised by man and incapable of being cleaned of corrosion. I soldered 2 new ones in.
Finally, the pcb and fuse are mounted on a plastic tower and vulnerable to 'splashes', so I covered the tower with an thin inverted plastic bag.
At the float take your (old) toothbrush and clean around to dislodge any wayward paper as there's not much clearance, and all should be well..

Thank you for the technical info I’ve saved it as I’m sure I will need it one day. But whose toothbrush should I use to clean the float?
 
Mar 24, 2014
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otherclive said:
chrisn7 said:
The connections to the C250 pcb clip directly to the board, but the copper tracks are very thin and corrode away to nothing. My solution was to follow the track a little, clean it and solder the wiring directly, eliminating 2 potential failure points.
At the fuse, the terminals to this are the most complicated devised by man and incapable of being cleaned of corrosion. I soldered 2 new ones in.
Finally, the pcb and fuse are mounted on a plastic tower and vulnerable to 'splashes', so I covered the tower with an thin inverted plastic bag.
At the float take your (old) toothbrush and clean around to dislodge any wayward paper as there's not much clearance, and all should be well..

Thank you for the technical info I’ve saved it as I’m sure I will need it one day. But whose toothbrush should I use to clean the float?

Whoever isn't around to see??
 

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