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Help, new to Fisher plow, lighting problem

Discussion in 'Fisher Engineering Discussion' started by macplee, Jan 30, 2009.

  1. macplee

    macplee Junior Member
    from Boston
    Messages: 19

    I am new to this site and to snow plowing. I just purchased a 2001 Dodge Ram with a 8' MM Fisher plow.

    The passenger side plow light didn't work so I changed the all in one light/bulb. But it still does not work with the new light. When unplugged, the truck's lights works perfect. When plugged in the plows sidemarker and driver side light works, but not the passenger side light.

    The isolation unit is a 4 plug system. I traced all the wires leading to the isolation unit and they all seem fine. Is this a common problem? Do you think it's the isolation unit?

    Any help would be appreciated.

    Paul :realmad:
  2. 06Sierra

    06Sierra PlowSite.com Addict
    from Maine
    Messages: 1,329

    Dumb ? but is the headlight switch on? On mine the driver side DRL doesn't work but when I turn the switch on, or it's dark enough for the lights to come on, it works fine.
  3. macplee

    macplee Junior Member
    from Boston
    Messages: 19

    Headlight switch on plow light passenger side still don't come on. As soon as I unplug the plow light wire, both the vehicle headlights comes on and works fine.

    The only thing I can think of is something wrong with the iso unit. Any thoughts?
  4. Crash935

    Crash935 2000 Club Member
    Messages: 2,377

    Theres a good chance that the yellow and blue wires in the harness need to be switfched or the configuration plug in incorrect and the wire needs to be switched to the other side of the plug.
  5. toyman

    toyman Senior Member
    Messages: 111

    Or the light that is not working properly has a bad ground.
  6. Dubliner

    Dubliner Senior Member
    Messages: 130

    I have an 01 Dodge with the same problem, left light was very dim, so I went to the plow garage and they replaced the light harness from the ISO box out. Worked until the first lot then went out, both beams. I will take it apart tomorrow to see if I can find a fix. It may just need a new bulb....but who knows.
  7. macplee

    macplee Junior Member
    from Boston
    Messages: 19

    Thanks for the replies. I finally figured it out. The problem is within the hard plastic connector where the vehicle's headline connector plugs into. I tested it with a multimeter and was shocked. I will need to replace entire wiring harness to the passenger side headline. Any idea how much that would cost me?

  8. macplee

    macplee Junior Member
    from Boston
    Messages: 19

    Question, where can I buy Fisher wiring harness? Can't find anything online.
  9. fisher guy

    fisher guy PlowSite.com Addict
    Messages: 1,068

    ebay sometimes craigslist sometimes but other then that u guessed it the dealer
  10. Dubliner

    Dubliner Senior Member
    Messages: 130

    Got mine from a local Fischer dealer, cost me $114. Be sure to use dielectric grease in your connectors or they will corrode and mess up, I apply it every third or fourth hook up.
    Last edited: Feb 1, 2009
  11. macplee

    macplee Junior Member
    from Boston
    Messages: 19

    I was lucky enough to find just a replacement connector on the web for just $10. The part is obviously not from Fisher, it was for some special after market headlight, but it will work and for much less. As seen in these photos. The gray connector is the one with the problem. The replacement connector is also pictured. I also have the URL if case it this may help others.

    Thanks for all you help.


    Can't attach image. Email me if you are like to see the photos. That's a pain.
  12. glen100

    glen100 Junior Member
    from Mass
    Messages: 7

    I have the same problem, The vehicle lights work fine but when I plug in I get one light that works in the truck and one that works on the plow? Anyone have an answer?