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Help, used MMII wiring help needed please!

Discussion in 'Fisher Engineering Discussion' started by TP from Central, Oct 30, 2011.

  1. TP from Central

    TP from Central Junior Member
    Messages: 3

    Hi Guys, bought a used 9 ft plow that was on an 1-ton GMC dually which was an '00 I believe, anyhow, got the iso. module, harness, the works...........We are putting it on a '01 2500 HD Chevy, and I got the main parts in, and have the headlight harness's from ports 3 and 4 hooked up to try it because I wasn't sure if everythign would work. Everything plugged into the headlights on the '01, and I spliced the two in on the drivers side, and one on the passengers side as per the print out I got on fishers website. Anyhow, everything worked on the truck except the driverside low beam, directions said about the wire change on the harness if that happened and it didn't do anything.................Plug the plow in and have everything except the low beams. Could someone here please point me in a direction to check because with the iso module and not knowing how/where everything goes I am just guessing. We got a awesome deal on this plow and its hardly used so would like to try and get eveything working properly. Plow will only be used on our farm.

    Thanks, I appreciate it.
     
  2. abbe

    abbe Senior Member
    from RI
    Messages: 719

    not sure if the configuration plug may have something to do with it? or the light harness. which is the number 2 lead off the module
     
  3. buddymanzpop

    buddymanzpop Senior Member
    Messages: 599

    Was the 2000 truck the wiring came from a "classic" body design like the 1998 body style? If it is you have a situation, let me know before I go any further, I know the 2001 is the changed Silverado body style, in 2000 they had "classic" and "Silverado body styles on 2500 and 3500's.
     
  4. TP from Central

    TP from Central Junior Member
    Messages: 3

    Yes, it was the old GMC style because they didn't change the GMC's till 01 right? Either way it was. Thanks for the help!
     
  5. 06Sierra

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

    Is it just one low beam that doesn't work?
     
  6. buddymanzpop

    buddymanzpop Senior Member
    Messages: 599

    Okay, that's your problem, for some strange reason the electrical engineering wizards at GM decided to change electrical systems on the new body style Sierra's and Silverado's from a positive common to a negative common system, then in 03 they went back to the positive common, so 99 to 02 1500's and 00 to 02 2500 and 3500's are affected by this, you can use a pick tool to reconfigure the wiring in your plugs to make this wiring work, you probably have the white label isolation module, you should have a green or yellow label module but the white label will work your DRL's just won't be transferred to the plow lights. If you think you have the ability to reconfigure the plugs, PM me your e-mail address and I will send you wiring guide which will show what color wires you need to move where.
     
  7. 06Sierra

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

    Mine came off an 01 and is on an 06. I don't have the drivers side light when it is running off the DRL. However, I do have both lights function correctly when I turn the switch on or when it is dark enough for the lights to come on. Never really knew why until now. Thanks.
     
  8. buddymanzpop

    buddymanzpop Senior Member
    Messages: 599

    Yes when dealing with the 4 port systems different wiring is required for the headlights, however Fisher DD figured out a way to make reversable headlight plugs when they came up with the three port system so the same wiring can be used on all GM's with hb3/hb4 lights,
     
  9. TP from Central

    TP from Central Junior Member
    Messages: 3

    PM sent.............Thanks Guys
     
  10. brad96z28

    brad96z28 PlowSite.com Addict
    Messages: 1,526

    U can reverse them on the gms, u just push real hard I do it all the time.
     
    Last edited: Oct 31, 2011