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2005 GMC 2500 high beams on all the time

Discussion in 'Fisher Engineering Discussion' started by rmoto113, Dec 17, 2008.

  1. rmoto113

    rmoto113 Junior Member
    from Maine
    Messages: 3

    I just bought a 2005 GMC 2500 6.0 and had a Fisher MM2 plow setup on the truck put on. My problem is the truck high beams are on all the time. If I shut my truck lights off I can use the high beam lever and flick the lights on so I know its not the switch. I also noticed when plow is not attached both the high and low beams stay on all the time. When Plow is on the Intense fire lights on plow are on high beam.

    I have a Yellow Isolation Module. I tried to see what the Part #'s on the light harness's were but they are faded (apparenlty I was given used stuff). Anyone have any ideas what could be going on. The help would be greatly appreciated. Also what ISO Module and light harness's part numbers am I suppose to have.

    Thanks :)

    PLOW_GUY Junior Member
    Messages: 21

    You have the wrong light kit you need a green labeled module for that truck. Which for a four port system is a 27780 kit
    Last edited: Dec 17, 2008
  3. 06Sierra

    06Sierra PlowSite.com Addict
    from Maine
    Messages: 1,328

    Just for fun, unplug the connection from the plow to truck, flip on end of the connection and plug in. The plow I bought, MM1, came off an 01 GMC. Has the 4 port iso and I had the same problem exactly. I just had to switch the two wires around on the plowside light connection.
  4. rmoto113

    rmoto113 Junior Member
    from Maine
    Messages: 3

    I will contact dealer and get the correct ISO Module. Thanks very much