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Fisher MM Issue - Plow stuck in upright position

Discussion in 'Fisher Engineering Discussion' started by MrPlowMass, Oct 23, 2011.

  1. MrPlowMass

    MrPlowMass Junior Member
    from Mass
    Messages: 7

    Hi All-

    I am new to posting here, but have lurked for some time - so official hello!

    I have a MM system on a 2000 GMC Sierra. I was going through the usual motions of checking the plow functions before the season and low and behold, everything works fine except that it will not go down...up, left and right (and lights) work just fine (though up does cause the plow to pivot left at an extremely slow rate which does not "usually" happen)

    I went through the manual and didn't find much in the way of help. I did check, and replace tested, the 2 harness fuses which didn't change anything.

    Does anyone know what else I can rule out? Right after posting this I am going out to see what I can do with the joystick as that could be a culprit.

    Any help is greatly appreciated!

    Thanks,
    Tony
     
  2. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    After you check out the controller, make sure the packing nut is not too tight, if that's not the problem then there is a little thing in the valve block called a poppet valve check this out, had this happening to a friend last winter and when we pulled the poppet we could clearly see it was broken, your next step after that is the valve cartridges. Good luck
     
  3. MrPlowMass

    MrPlowMass Junior Member
    from Mass
    Messages: 7

    Thanks for the response Buddy.

    Well, the packing nut did seem REALLY tight, so I got that to the point where it shot fluid all over the place including all over dad (oops). Now that the packing nut seems to be at a more reasonable tightness, it still does not go down. I checked the solenoid power - that seemed to be the only one that was getting juice to it as a constant (meaning not having to use the joystick to get power to it as I had to do for left and right testing).

    I wasn't able to make much sense/progress with the joystick mechanisms because I cannot seem to find a way to test out the various point in the 6 point harness which connect to the joystick (can anyone point me in a direction here please?)

    Also, I direct wired the solenoid positive to the battery positive and it dropped, would that rule out a valve issue?

    Thanks again,
    Tony
     
  4. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    Can you borrow a "known good" controller and try your plow system out with it, that's the easiest way to find a bad controller. Where in Ma. are you, maybe someone here that's nearby can help with theirs.
     
    Last edited: Oct 23, 2011
  5. MrPlowMass

    MrPlowMass Junior Member
    from Mass
    Messages: 7

    Fantasic idea, I have one in my Ford. It's got a MMII but I do not think that should matter - they are both the same unit.

    Will let you know what happens.

    Thanks!
    Tony
     
  6. MrPlowMass

    MrPlowMass Junior Member
    from Mass
    Messages: 7

    Well, the other joystick also did not make it go down. :(

    I suppose I can try changing out the solenoid to rule that piece out next.

    Thanks again for the ideas Buddy.
     
  7. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    I don't think it's your solenoid, the solenoid would either work or won't work, remember the plow motor does not use power to lower, locate your poppet valve and see if it is broken.
     
  8. equip guy

    equip guy Member
    Messages: 38

    I had this happen last season. It ended up to be the "truck side" harness at the plug at grille area. The pin positions for that function had been played out and were not making a good connection inside the rubber boot assembly. Try to wiggle or slightly twist the plug which controls the plow functions while someone else attempts to lower the plow. SAFETY NOTE: use extreme caution while do this diagnostic procedure. Try to stand to the side of truck not in the pivot or blade drop zone,
    If you get the function back or the plow acts erraticly, the harness with plug needs to be replaced. Fisher offers a replacement that you only replace the plug with a short pig tail which splices in with shrink tube butt connectors. Also the coil packs should be not tighter than 5 inch pounds or basicly once the nut stops, move only 1/16th of inch past. Thats it. Hope this helps
     
  9. rmartini27

    rmartini27 Senior Member
    Messages: 118

    Sounds like a poppin vaulve to me, had one two years ago and it broke this tiny spring. To this day every once in a while the plow will not drop and will only turn left or right. I have removed and blown out that valve body like 5 times and it still has problems. Good Luck
     
  10. rmartini27

    rmartini27 Senior Member
    Messages: 118

    Sounds like a poppin valve to me, had one two years ago and it broke this tiny spring. To this day every once in a while the plow will not drop and will only turn left or right. I have removed and blown out that valve body like 5 times and it still has problems. Good Luck