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Fisher MM1 moves really really slow

Discussion in 'Truck & Equipment Repair' started by nichols, Dec 8, 2009.

  1. nichols

    nichols Member
    Messages: 47

    Hi all,

    I have a 2-plug 7'6" MM1 that's been working fine for a number of years now. This year, I bought a new truck (2009 Silverado 1500) and swapped the plow over to the new truck. I came from a 2002 F250 diesel.

    I bought a used wiring harness for a 2-plug fisher, and pieced it together to work with my truck. The harness used a round 9? pin plug to connect to the controller, so I converted it to the rectangular 6-pin plug for my joystick. I get 12v to all of the valve pins that I should for each direction for the joystick, the lights all work, etc.

    When I hooked up the plow for the first time tonight, I found that the movement in any direction is ridiculously slow - we're talking 15-20 seconds to raise it all the way, and 15 or so seconds to angle the plow only a few degrees left or right. I added fluid because it was a little low, and then pulled the pump. It seems to spin freely without any notchiness.

    Could this still be a bad pump? I'm going to try plugging into another 2-plug plow tomorrow to see if it's possibly something wrong with the truck wiring, but all of the motor solenoid clicks when I hit the controller, and I assume that because the pump is getting power at all, the motor solenoid works.

    I store the plow in the garage during the spring/summer/fall, and it worked fine before I put it away last. The only thing I can think of is that my old truck had two batteries, whereas this one only has one, so maybe the old truck with more battery juice was masking a problem I didn't know I had, maybe? I only plow my driveway and my grandparents' driveway, so the plow sees pretty light use.

    Any suggestions for other things to potentially check?

    Thanks in advance, everyone.
    Last edited: Dec 8, 2009
  2. Wildman_fab

    Wildman_fab Junior Member
    Messages: 9

    If you can find another plow to plug in I would say go for it. That will eliminate some of the guesswork and questions.
    I would also check your grounds! With all the wire swapping around there may be something loose or corroded that you didn't see when you threw it on there. The inside of the main solinoid may be corroded also and not making a complete circuit (I have had it happen on my truck the exact same way)
  3. no lead

    no lead PlowSite.com Addict
    Messages: 1,308

    have someone sit on the blade and hit up. if it wont lift the pump is weak.
  4. ticki2

    ticki2 Senior Member
    from NH
    Messages: 175

    could also be a clogged filter
  5. dbduts

    dbduts Member
    Messages: 59

    if the pump sounds strong I would check filter and change fluid you can take out old filter and clean it with carb cleaner or if pump turns weak check all connections you can jump out main solenoid and see if plow turns better
  6. nichols

    nichols Member
    Messages: 47

    Thanks for all of the suggestions, everyone. It's fixed! Here's what I did:

    I also dug through the Mechanic's guide for the SEHP plow on Fisher's site, and ruled out the motor solenoid by tossing jumper cables on the pos and neg leads on the motor, and hooked them up to the battery. The motor didn't seem any stronger or weaker, so I figured the solenoid was ok.

    I pulled the motor and drained the fluid out of the pump reservoir and found a TON of sludge in there - especially around the magnet stuck to the pump, and on the filter. So, I siphoned out the fluid out of the reservoir, took the pump out, cleaned everything out on the filter, and reinstalled. While I had the motor off, I cleaned up all of the contacts, popped the top off to inspect the brushes just for kicks, and blew all of the dust out of there.

    Reassembled everything, and it's good as new! Thanks again!!!