Thetford 402c won't flush

Discussion in 'Port-A-Potties / Cassette Toilets / Bath Houses' started by Thorofin, Jul 25, 2020.

  1. Thorofin

    Thorofin New Member

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    So I have recently reassembled a wetbath in my Aliner that the previous owners had removed.

    I just finished getting the toilet in place, with the cartridge. I have been trying to get it to flush, and have not had any luck with using the flush button.

    Fuse is good, I get power to the board. Pump is good, and pumps water into the bowl when I jump it from the incoming lines.

    My next thought was the flush board was bad, so I purchased a replacement, and installed it today, and still nothing happens when I hit the water button on the pump.

    I'm stumped where to go from here troubleshooting.
     
  2. Thorofin

    Thorofin New Member

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    I'm still hoping someone has some ideas to identify the issue with this. In the interim, I found the Troubleshooting & Repair guides for the 400 series toilets
    http://www.thetfordservicenet.com/
     
  3. Sjm9911

    Sjm9911 Well-Known Member Gold Supporting Member

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    Maybe the button is bad? Mine wasn't ellectric.
     
  4. Thorofin

    Thorofin New Member

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    The button is part of the flush logic board, which has already been replaced.
     
  5. Sjm9911

    Sjm9911 Well-Known Member Gold Supporting Member

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    Any way to test the new board? Wouldnt be the first time someone has gotten a bad part. Should only be pump fuse and wires. Any way to get rid of the board and just add a push button switch?
     
  6. Thorofin

    Thorofin New Member

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    I haven't figured out a way to test the board yet. If someone can tell me how to test the board, that would be awesome.
     
  7. WrkrBee

    WrkrBee Well-Known Member Silver Supporting Member

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    From CaravanTalk webpage:
    I previously spoke with my mobile service engineer and he said that in the last 2 years he had to replace 1 or 2 reed switches, 2 or 3 circuit boards, but dozens of pumps were the source of the problem.

    Having removed the pump I could see the rotor vanes would not turn. ...because dried blue solution was gumming it up. Once cleared, it worked fine.
     
  8. Thorofin

    Thorofin New Member

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    Thank you. The pump was one of the first things I checked, based on my searches. The pump works if I wire it directly to 12v, so I eliminated that as an issue. I will start looking at the reed switch. And overall, I'm looking for ways to troubleshoot these components.
     

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