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8'hd mm1 SEHP no movement at plow! Help!

Discussion in 'Fisher Engineering Discussion' started by SinisterSnake, Nov 7, 2011.

  1. SinisterSnake

    SinisterSnake Junior Member
    Messages: 11

    I just installed an 8' Fisher HD MM1 plow on my 2003 F250. The pump on the plow is the SEHP.

    I've got power at the fishstick. The motor runs. When I select a direction (Up, left, or right) the motor runs but the plow doesn't move.

    I checked the screen, that's clear.

    I tuned the pump by hand when I had the motor off and it was visibly moving fluid.

    I put in all new fluid and drained the lower rams and filled those as well.

    Where should I look next?


    Thanks!
    :mechanic:
     
  2. buddymanzpop

    buddymanzpop Senior Member
    Messages: 599

    Check your ground to your valve coils, small black/orange wire coming from your valve coils , there's one ground to all three coils.
     
  3. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    Is this a 2 plug or 3 plug setup, do you have an ISO Module or Relay System ?

    I concur with Buddy, I would first start by checking to see if that lead ground is in fact connected. However I think something else is going to be the culprit.
     
  4. SinisterSnake

    SinisterSnake Junior Member
    Messages: 11

    It's a two plug.

    The grounds are connected.

    Do those coils make any noise? I don't remember them making noise when I select a direction.
     
  5. buddymanzpop

    buddymanzpop Senior Member
    Messages: 599

    You can have someone check for magnetism at the coils by using the controller to request a function from the plow, you'll feel the screwdriver get pulled to the end of the coil, let us know how that test goes. The coils do not make noise they open and close the valves through magnetism and you won't hear the valves opening and closing when they are in the valve block. This test will confirm power and ground. Finding your problem will be a process of elimination. It would be nice if you could test the psi output of your pump.
     
  6. SinisterSnake

    SinisterSnake Junior Member
    Messages: 11

    Ok, I will check the magnetism after work today and report back.

    I have no way to test the psi of the pump.


    Thanks!
     
  7. SinisterSnake

    SinisterSnake Junior Member
    Messages: 11

    I checked the magnetism of the coils and all three pulled on my screwdriver.

    Now I'm really stumped. I don't really want to pay the dealer to diagnose this. Any other ideas?
     
  8. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    All this proves is that the coils are activating, and if done right, that your wiring is correct. It does not prove that the Valves, and or the Pump are. You need to dig further to see where your issue is.

    Pull your motor and wiring, drain the fluid, pull your coils and valves as well as your pump. Remove the o-ring that sits beneath the pump, as well as the screen filter on the pump. Get parts 5820 & 5821 from your dealer to replace them. Make sure the shaft on the pump doesn't have any play to it, and that it turns smoothly.

    Thoroughly clean the reservoir while you have it apart.

    Clean the ports where the valves were with a can of carb & choke, or brake cleaner. Inspect the o-rings on each valve and replace them with OEM Fisher ones if so damaged. They sell O ring packs for each valve, if you need help finding the part # ; let me know which valve is in need of a new o-ring, and I can get you a kit number. Pop in the end of each valve with a pointy object, they should push in with little effort, and spring (spool) back once released. If they don't, clean and repeat. In the off chance that any of them are still not operating smoothly, replace. If all stick, then release with some pressure....then this was most likely your issue to begin with.

    Do you have a pressure test kit?
     
  9. SinisterSnake

    SinisterSnake Junior Member
    Messages: 11

    Sounds good.

    I do not have a pressure test kit.
     
  10. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    No worries. Chances are you'll clean away the issue, or find that your pump is toast.
     
  11. SinisterSnake

    SinisterSnake Junior Member
    Messages: 11

    Thanks for the advice. Hopefully I can get it all apart tomorrow.
     
  12. SinisterSnake

    SinisterSnake Junior Member
    Messages: 11

    New valves are in. Two were bad so I replaced all of them.


    It now moves up and left!!!!!

    That means I have no movement to the right. :(
     
  13. SinisterSnake

    SinisterSnake Junior Member
    Messages: 11

    Poppet Valve was replaced. Didn't solve the lack of angle right :(
     
  14. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    Defective valve maybe. Double check your wiring at the coils. Then check for mag. while angeling right. If it checks out, pull valve and exchange.
     
  15. SinisterSnake

    SinisterSnake Junior Member
    Messages: 11

    I've double checked the wiring. All magnetized.

    The truck/plow is now at the dealer. They said they'd diagnose it for a $70/hr, max of one hour, less if it's a quickie.

    Then I'll get what they tell me and fix it.
     
  16. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    Very odd scenario . I'll be interested to hear the out come.
     
  17. SinisterSnake

    SinisterSnake Junior Member
    Messages: 11

    They sold me the WRONG valve!!!!

    I took my old three in, set them on the counter, and said "I need these". Somehow I ended up with a valve for a V-plow.

    They took it out put in the right valve, and changed my hoses for $53. I was happy.


    Thanks for the help Repoman.
     
  18. RepoMan207

    RepoMan207 PlowSite Fanatic
    from Maine
    Messages: 5,031

    I knew something was fishy. That would explain it for sure. Happy plowing!