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Headlight problem Fisher mm2 HD 4 port unit

Discussion in 'Fisher Engineering Discussion' started by RipSaw, Nov 14, 2014.

  1. RipSaw

    RipSaw Junior Member
    Messages: 12

    HI this is my first post... I have a 2007 Chevy (classic)2500 HD Ext cab. I hitch up the isolation unit (4 port) and all wiring to my truck. the issue is that both low/high beams are on at the same time. The hi beam switch dose not make any changes when used. And I have removed both wiring harness and it function fine without them in. Plus change out the relay switch just to see, no change. I also unwrap both wiring harnesses to check for any damage and there was none. Any help would be greats... Thank you RipSaw
     
  2. LON

    LON Senior Member
    Messages: 749

    You have a 27780 light kit with a 27781 light green label module?
    26351 short harness & 26352 long harness for HB3/HB4?
     
  3. RipSaw

    RipSaw Junior Member
    Messages: 12

    I have both a green and a yellow tag ISO unit
     
  4. RipSaw

    RipSaw Junior Member
    Messages: 12

    I tried them both with the installation it made no differents
     
  5. RipSaw

    RipSaw Junior Member
    Messages: 12

    I have been looking around ... I have a dust cover in my harness do I need the configure plug instead?
     
  6. chevyzrule810

    chevyzrule810 PlowSite.com Addict
    Messages: 1,238

    You should have two dust cover plugs.The first is for the 15 amp fuse for the park/turn and the second is a 7.5 for the controller.Your headlight plugs could ether be plugged in positive instead of negative, or negative instead of positive.To switch the plugs refer to page 4 here http://library.fisherplows.com/fisherplows/pdffiles/28561.04_052407.pdf
     
  7. LON

    LON Senior Member
    Messages: 749

    No configuration plug on a GM. I usually just grease the plug shut to keep corrosion at bay.
     
  8. LON

    LON Senior Member
    Messages: 749

    Did you check the part number tags on the headlight harness's?
    Yellow label module was for 99-02 GM with 26360 & 26361 harness's
     
  9. RipSaw

    RipSaw Junior Member
    Messages: 12

    My harness for port "3" is 26289
    "4" has no label
     
  10. LON

    LON Senior Member
    Messages: 749

    Wrong harness's. Need to find right ones
     
  11. Bakernator

    Bakernator Junior Member
    from Maine
    Messages: 8

    Is there any way to change pins? I am encountering the same issue with mine.
     
  12. LON

    LON Senior Member
    Messages: 749

  13. Bakernator

    Bakernator Junior Member
    from Maine
    Messages: 8

    I fixed mine today and had the same issue. Try swapping the pins in the male and female connectors on the headlight harness on both sides. My harness came from an 01 and my truck is an 06. I changed over the connectors and now it works fine.
     
  14. RipSaw

    RipSaw Junior Member
    Messages: 12


    Well I will give that a shot ... If it works that will be great ... I will let everyone know ... And thanks for everyone's input
     
  15. RipSaw

    RipSaw Junior Member
    Messages: 12

    Hi everyone I wanted to update everyone on my progress...I did switch the pins in the harness and that was the problem ...it was easy took twenty mins or so ... Thanks for all the help