C2 thetford flush problem

Discussion in 'Motorhome Chat' started by Davfo42, Jul 29, 2015.

  1. Davfo42

    Davfo42

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    Sorry, but have to put this one out to the team of experts. I have a thetford c2 toilet system. It doesn't have a separate tank for the flush. Since i bought the Hymer, the flush button never turned on the pump, but if I had the tap running in the sink in the toilet previously, when I push the flush, water does come out of the toilet bowl flush pipe. I thought it might be the flush mechanism, so I bought a new one and fitted it, no change. I am attaching a photo of the cable loom going to the toilet. (the grey cable with brown, blue, black and black/white. ) this connection box is under the sink in the toilet. Does anyone know what voltage readings I should be getting across this cable to ensure I am getting the proper supply to the flush mechanism. regards
    Dave
    IMG_3355.JPG IMG_3355.JPG
     
  2. JeanLuc

    JeanLuc Funster

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    I suspect the fault is with the toilet flush switch which is not activating the pump. The fact that water runs though the flush system when a tap is switched on implies this as the pump is activated by a micro-switch turning on. There are switches in the taps and the toilet flush system. I have documentation for the later C200 but not the C2 so cannot suggest where to find the switch on yours. also, check if there is a blade fuse somewhere under the toilet and check if this has blown.
    Just a word of caution in case you have not noticed it: Hymer normally use blue or black for +ve and brown for -ve 12v wiring but check this with a multimeter.
     
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  3. Dave and Ginny

    Dave and Ginny Funster

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    I have a C3 and the same problem occurred a few months ago, no flush. I didn't try what you have done and that was to run the sink tap with the toilet valve depressed. What it turned out to be on mine was a wire breaking due to the fatigue of the toilet valve opening and closing. It was a nightmare to see up into, but I found using my phone to take a pic was a great help! Worth you having a look, this is the bottom of the flushing valve that locates in the cassette. It has ( seem to recall) two micro switches; one closes as a safety feature to stop you flushing when the cassette is removed, the other operates when you push the valve to flush. You can remove the entire assembly by that central self taper.

    You can just about spot the broken brown wire in this pic. Dropping the it down just gave enough room to effect a 'temporary' fix that's still in place!

    PS...as @JeanLuc says, check the fuse first...you can see it in the pic.

    20150422_122859.jpg
     
  4. Davfo42

    Davfo42

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    Hi
    Thanks for all the replys, however i have already put a brand new assembly mechanism. checked all fuses etc, I even checked the old one- all the wiring and micro switches were all 100 % on that, so i am wondering were the positions of the loom in the picture in the wrong place possibly.
    davidandginny , you have the same loom as me (grey outer, ble, brown, black, black/white, do you have any idea what readings i would get off these with a multi, so i would know there is no break on the cabling............big ask i know
     
  5. Dave and Ginny

    Dave and Ginny Funster

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    Sorry being so slow getting back...Oh dear, can't help I'm afraid with that one as I have absolutely no idea what the readings should be. I've never been great with electrics unless I see the obvious like a broken wire! I know my wiring also goes by way of a relay that sits underneath the loo role case which just pulls out but I'm guessing you have probably already tried that? I had read somewhere that the relays are prone to failing. Hope you get it sorted though. Dave
     
  6. Davfo42

    Davfo42

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    Thanks Dave, i have been a bit busy this week tending to loose ends before i can concentrate on holidays,... actually did not know anything about a relay. what does that look like. i am sure i would have seen it by now. I will be taking another close look in the next few days. Thanks again for the replies. David
     
  7. Dave and Ginny

    Dave and Ginny Funster

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    I've just been looking at the C2/C3 and there are differences as my water comes from the main tank and yours from a separate holding tank, so I could be misleading you! When I said relay I should have said valve, which is probably on mine to prevent water running back from the loo into the water supply. I did find this though, and if you click on the link for spare parts list it give some good diagrams that may help. Dave


    http://www.thetford-europe.com/?s=c3[/QUOTE]
     
  8. Davfo42

    Davfo42

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    Hi Dave, my water also comes from the main tank. So i probably have exactly the same as you.
    i will check out the web site you posted. cheers
     
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  9. Dave and Ginny

    Dave and Ginny Funster

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    Ah, in that case you should find the valve if you pull out the casing of the loo role holder! :)
     
  10. Davfo42

    Davfo42

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    hi, just got a chance to look under loo roll holder.....voila, there it is ......a relay,, and a small cylinder connetcted to the pipes which must be the valve you are talking about. the fact my pump does not come on when the flush is pressed would seem to hint that the relay is the probable fault. can the relay be tested, or maybe i should just get one and try it.........................................just a thought..............can the relay be by passed for testing purposes......
     
  11. Davfo42

    Davfo42

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    it would appear that my thread title is incorrect, the thetford spares list show i have a C3 system which is different than the C2.
     
  12. Dave and Ginny

    Dave and Ginny Funster

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    @Davfo42 Not sure if by-passing it to test is possible or not, but looking at the diagram again there is a relay and a valve. In your initial post you say that when you operate the toilet flush with a sink tap running you get water out of the toilet bowl? When mine packed up I tried that and got nothing, if your getting water then that would suggest the valve is either opening or stuck open maybe? When I flush mine I hear that valve open with quite a loud 'click', do you get this with yours or just nothing? A wiring diagram would help, I've had a quick look on google but not found anything.
     
  13. Davfo42

    Davfo42

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    i get no sound. does that suggest the valve is the issue???
     
  14. Dave and Ginny

    Dave and Ginny Funster

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    Well you should hear the valve operate, it's quite loud and distinct in mine. The valve has to open to let water through, I presume the relay operates the valve but whether that also sends power to the pump I've no idea. This is where a wiring diagram would be handy! If it were me I would check out the prices of the relay and the pump and if not too dear replace them...relay first.
     
  15. Davfo42

    Davfo42

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    ok i am on it, just to recap though, my pump in the water tank works (as proved by the taps in the kitchen and toilet) but the valve is not opening, so i will order a valve and a relay, and if this doesnt work i will buy a plastic cup (to fill with water, and flush down the loo)
    Thanks for your help. its good to bounce a problem off someone. i will keep you posted. it will be next week before i get the parts so dont wait up. cheers Dave
     
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  16. Davfo42

    Davfo42

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    ok, just for the update, I have found the electric valve and relay, I took the leads off the electric valve and metered them , pushing down on the flush . A twelve volt supply is present when i push down the flush . I replaced the leads on the valve and low and behold I could hear and feel the valve open and close as I push down and release the flush, so I can only presume the valve is doing its job.
    My next question is:::::::::: should the pump in the main water tank come on when i push down the flush (it isnt coming on) ????. if it should,, then one output of the relay may be gone, is this correct?? ps i did also take the leads off the relay, clean the contacts and as i replaced the connecter i could feel a switching taking place place in the relay housing. So this leaves the fault with the (1) relay, (2) the lead back to the pump (3) the vacuum assembly , which i have no idea how that works.
    I am so close.......i feel it in my bones.........so close....ggrrrrrhhh
     
  17. Davfo42

    Davfo42

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    ps, i now know that i have a C3 not a C2 as the post is titled
     
  18. tonyidle

    tonyidle Funster

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  19. jollyrodger

    jollyrodger Funster Life Member

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  20. Dave and Ginny

    Dave and Ginny Funster

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    There has to be a wiring or circuit diagram available from somewhere one would have thought!...I keep looking but haven't come up with anything! If you have power to the valve and hear it operating I would have thought the relay must be working as that, I would have thought, operates and takes the load from the valve which must be some kind of solenoid operating device. Just a thought, but could you take a wire from the live at the valve/relay and run it to your pump and see what happens? . I can't see it would do any harm trying....he says tentatively :cautious:.

    PS...sorry about all the 'thoughts' and no definite's o_O
     
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