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Fisher MM1 plow issues (lights, won't go down) - help?

Discussion in 'Fisher Engineering Discussion' started by mm1plowman, Sep 17, 2011.

  1. mm1plowman

    mm1plowman Junior Member
    from Mass.
    Messages: 2

    Ok, so I have a new (to me) 1999 F250 with a Fisher MM1 plow. This is a 2-plug setup.

    When I picked it up, everything was working ok. That was a few weeks ago. I disconnected the plow and let it sit in the driveway.

    Last week, I went to hook it up, and noticed that the headlights wouldn't come on in the plow. I checked, and found that the plow had been rewired with a new plug wiring kit at some point. I unwrapped the wiring, and found that the 3 wires were broken and not connected and the plug was in generally poor shape. So, I ordered a new plug. Note that at this point, I didn't try using the plow, so I don't know what else was not working.

    Today, I carefully removed the old plug, cleaned up the wiring, and rewired the new plug. The headlights still won't work. Also, the plow won't go down (it will go up, left, right.)

    I checked, and the wiring to the S1 (yellow/white wire) appears to be working fine when I put set it to float - I get power to the yellow/white wire (as evidenced by the circuit tester I used.) When I connect/disconnect the yellow/white wire on the solenoid, I can hear a "click-click". So, I removed the valve, and using a small, clean rod, it moves in/out about 1/8" or so (not much more than that.) Is that the normal amount of movement? I put it back in, and the piston still won't budge.

    Now, an interesting thing is that when I removed the valve, the piston still didn't go down. I didn't push on it with it out though (not wanting to lose any more fluid than necessary. :) ) Should the piston go down with the valve removed?

    Basically, any ideas, on either the headlights or the piston not going down? I'm willing to order a new valve and give that a shot, but I'm not sure if that is the issue.

    Also, I did notice that even when the plow is not connected, the controller will light up the on LED when I turn it on and off. I thought that it was only supposed to do that when the plow was connected? Could that indicate a wiring problem?

    Thanks a lot for any and all replies/advice. This is my first minute-mount (I've used many speedcasts in the past...)

  2. Kwing1120

    Kwing1120 Member
    Messages: 39

    I can't really offer ay hep other than my LED would come on the joystick even when the plow was not connected. it was a 7'6" MM1.
  3. mm1plowman

    mm1plowman Junior Member
    from Mass.
    Messages: 2

    Thanks, that makes me feel a little better. ;-) Electrically, everything seems fine (but maybe I need new headlight relays?)

    Still can't get the plow to go down. I tried to loosen the packing nut, but it's frozen solid. I put some penetrating oil on it, and will let it sit and try again - I don't want to break or strip it...

    Any other ideas are more than welcome. Thanks!
  4. 1/2tonthatcould

    1/2tonthatcould Member
    from MA
    Messages: 35

    Not likely the answer to your problem, but I actually had to cut open the braided loom on my harness, I found fisher factory but connections that had broken, which was causing my lights to get 5 volts (ground wire). Just saying this is a possibilty.