C2 thetford flush problem (1 Viewer)

[Davfo42]

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

 

[JeanLuc]

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.

 

[Dave and Ginny]

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.

^{_{Subscribers  do not see these advertisements}}

 

[Davfo42]

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

 

[Dave and Ginny]

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

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

 

[Davfo42]

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

^{_{Subscribers  do not see these advertisements}}

 

[Dave and Ginny]

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

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]

 

[Davfo42]

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

 

[Dave and Ginny]

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

Ah, in that case you should find the valve if you pull out the casing of the loo role holder!

^{_{Subscribers  do not see these advertisements}}

 

[Davfo42]

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......

 

[Davfo42]

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.

 

[Dave and Ginny]

@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.

^{_{Subscribers  do not see these advertisements}}

 

[Davfo42]

i get no sound. does that suggest the valve is the issue???

 

[Dave and Ginny]

i get no sound. does that suggest the valve is the issue???

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.

 

[Davfo42]

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

^{_{Subscribers  do not see these advertisements}}

 

[Davfo42]

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

 

[Davfo42]

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

 

[tonyidle]

This might help:

Broken Link Removed

Your diagnosis sounds correct so far although I'm not sure what you mean by the "vacuum assembly".

^{_{Subscribers  do not see these advertisements}}

 

[jollyrodger]

This any good to you

http://www.motorhomefun.co.uk/forum...-and-vacuumbreaker-replacement-with-pics.121/

 

[Dave and Ginny]

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

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 .

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

 

[Jaws]

To answer your question, yes, the pump SHOULD fire up when you press the button

^{_{Subscribers  do not see these advertisements}}

 

[Davfo42]

Thanks again for all the help. As I said, I am very close...tony you sent me a link to install instructions but the wiring diagrams cannot be read.
I have traced a black wire with white stripe back to a junction box under the bathroom sink.......... Which is the first picture I posted. This is connected to the junction box, But, there is no wire connected to it. This I presume is the wire that should be going back to the pump, I have touched it off a couple of the leads but when I press the flush I blow a fuse. ( I mean an electrical fuse, not my mind), If only I knew where this black with white line wire should be going.................... I will say it again...... I am this close....

 

[JeanLuc]

Just studied the wiring diagram for my 2003 Hymer Star-Line. May not help as the colour coding does not mention black/white but here is the basic system of cabling.
You need to look at the colour of the cables coming into the connector block. My diagram indicates the following:

• Brown - which comes from the 'Pump -ve' pin on the Elektroblock (EBL) and also connects to the brown -ve line to the pump
  
• Purple - which comes from the 'Pump +ve' pin on the EBL
• Blue - which goes to the Pump and should not have anything else connected to it (YET)

The cables from the toilet flush are then indicated as being connected as follows (different colours unfortunately):

• Brown to the connector that has Brown from the EBL (i.e. the -ve feed)
  
• Pink that connects to the Blue going to the pump (i.e. the +ve feed from the switch to activate the pump)
• Purple that connects to the Purple feed from the EBL (i.e. the +ve feed to the switch)

If we assume that your Thetford harness has Brown in common with the above, you then need to determine with a multimeter that Blue and B/W provide continuity when the switch is pressed. If so, they are the +ve feed and return to/from the switch Can you check from the other end of the harness, which is the connected to the output (load) pin on the relay? If so, I think that should then go to the connector pin that has the blue cable (or possibly purple cable) going to your pump.

Sorry of this is all a bit complicated but I am trying to verbalise what I am guessing you may see in terms of cables linked to your connector block.

 

[Davfo42]

update. to cut a long story short...........................I HAVE FIXED IT..............................YEEAAAAAAAAAAAAAGHHAGHAA........to give you the long story, i stripped the connector block, (in the original picture), after taking a note of where everything was of course, then proceeded to connect one thing at a time. this consisted of a 12v supply + and -, then my supply to the lights in the bathroom, then the supply for the bathroom tap, + - and switched wire, then wired up the tap, ........so far all working, tap in toilet, tap in kitchen, and lights in toilet. moving onwards, connected up the four cables coming from the flush on the toilet, + and - supply and lead back to pump. voila..... the flush worked.....brilliant i thought, until i switched on the tap and the toilet flushed as well, gggggrrrhh. i decided to get in the car and go the local car parts shop and get a new relay, which i did, for only €5. back in the the camper, put in the new relay and hey presto, normal service resumed. it had been the relay all along. The sigh of relief on my wifes face when i told her it was fixed, because she thought i was going to spend the whole of our holiday in france annoying every camper owner on site to come and help fix the flush on the jacksie. Thanks for everyones input..........and yes i know the relay was suggested from the word go,,,,i just didnt get the chance to buy one.
Now for a beer
off to france next thurs........cant wait
regards
David

^{_{Subscribers  do not see these advertisements}}

 

[Dave and Ginny]

Thank bloody goodness for that!