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Fisher MM1 2-wire issues

Discussion in 'Truck & Equipment Repair' started by Merc1100sc, Sep 21, 2015.

  1. Merc1100sc

    Merc1100sc Senior Member
    Messages: 245

    Hello all. I have an older electric Fisher MM1 on a 2002 Tacoma.
    I pulled it put yesterday to change the fluid and check everything.
    It's doing two odd things that it has not done in the past:

    1) The main pump motor solenoid sticks on. I had to tap it a couple times to get it to click off. This is a new Fisher solenoid I bought from the dealer last winter and installed. I wouldn't think it should be giving me issues already.
    I have it mounted sideways instead of flat on its base. Wondering if this could have anything to do with it.

    2) The blade will sometimes not move left. If I sweep right and then left and hold the control to the left it will move until the lock. If I stop mid way and try to go left the solenoids in the pump housing click but not the main pump solenoid and no movement. If I bump it right quick and then left it works. Almost as if the main solenoid(pump solenoid under the hood) is not getting triggered. Any ideas.

    Thanks
     
  2. linckeil

    linckeil PlowSite.com Addict
    from CT
    Messages: 1,265

    based on your post I can say with 98% certainty that your solenoid is bad/going bad. I've had brand new ones fail after one storm - i always carry a spare.

    I highly suggest using this one:

    http://shopping.murcal.com/Catalog/Bear-DC-Contactor-Family/114-1211-020

    its what I have now. these are super high quality - better than anything any OEM plow manufacturer offers. they are larger than the standard plow solenoids, so mounting it may be an issue. given the quality, the price is very fair.

    by the way, is your username in reference to a "tower of power"?
     
  3. Merc1100sc

    Merc1100sc Senior Member
    Messages: 245

    Thanks for the reply. I will def look into that solenoid.

    Any ideas on the problem I am having with swinging the blade to the left?
     
  4. linckeil

    linckeil PlowSite.com Addict
    from CT
    Messages: 1,265

    BOTH of the problems you describe are symptoms of a solenoid failing. when angling the blade left, you are shifting 2 valves (as opposed to 1 valve when going right or up). shifting 2 valves leaves slightly less voltage to go to the solenoid and when a solenoid is weak/ready to fail completely, that slight voltage drop is enough to keep the solenoid from activating at all. it's rare, but it's happened to me with the cheapie solenoids I have used in the past prior to getting the solenoid I linked above.

    if you want to prove this theory, check the voltage at the small positive wire feeding the solenoid when angling left. i'll bet you that voltage reading is less than when angling right or going up. that small difference in voltage is enough to keep a weak solenoid from activating. replace solenoid and both your problems will very likely go away.
     
  5. Merc1100sc

    Merc1100sc Senior Member
    Messages: 245

    What you are saying makes sense.
    Actually if I stick a test light on the solenoid trigger wire I get power with the up and right functions but not the left function always. I hear the solenoid on the pump valve body clicking but it doesn't send power to the main pump solenoid. Maybe the voltage is too minimal for my light to pick it up. I assumed something wasn't making contact in the wiring harness all the time causing this.