1. Welcome to PlowSite. Notice a fresh look and new features? It’s now easier to share photos and videos, find popular topics fast, and enjoy expanded user profiles. If you have any questions, click HELP at the top or bottom of any page, or send an email to help@plowsite.com. We welcome your feedback.

    Dismiss Notice

Help !!!!!!!!!!!!!!

Discussion in 'Fisher Engineering Discussion' started by overboost, Dec 15, 2012.

  1. overboost

    overboost Junior Member
    Messages: 5

    ok customer had me buy a used plow for his 00 gmc sierra. found one local guy was completely legit and has tried to help me .

    this is a mm1 2 wire from gmc (possibly a 98 or 99)

    so put the harness in he gave me plugged right into factory harness. wired everything else. plugged the plow in now .... both headlights on the truck side work one on high beam and low beam the other on low.....hit the high beam one goes to high beam the other goes OUT. plug the plow head in both lamps have one beam no low or high.
    no marker lights on the plow head no turn signals on the plow head. i have gone over everything two three and four times.

    WHAT AM I MISSING!!!!!!!

    would i be better off cutting into the factory harness and soldering this stuff into one side of the truck ?????????
     
  2. Morrissey snow removal

    Morrissey snow removal PlowSite.com Addict
    Messages: 1,799

    check ur grounds and the relays
     
  3. overboost

    overboost Junior Member
    Messages: 5

    ok found one problem. the harness was using a common ground for left and right high beam and low beam ran a seperate ground to the light i now have high and low beam left and right on the truck WHEW .......but the headgear only has one setting and is indicating on the cluster high beam no matter where you put the high low selector (this problem was there before just forgot to mention that .GRRR!!!!!!
     
  4. overboost

    overboost Junior Member
    Messages: 5

    new relays that was my first thought

    power probe to grounds and still have a minor headache now.
     
  5. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    More info needed on the 2000 GM. Is it a newer body style, 1/2, 3/4 or 1 ton or old body style 3/4 or 1 ton?
     
  6. overboost

    overboost Junior Member
    Messages: 5

    it has "aero" headlights (composite lense with replaceable individual halogen bulbs)

    1500 i believe

    it has drl's

    now i have it so when you flip on the high beams the head gear lights go out and truck lights go to high beam. so not the end of the world.
     
  7. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    Your headlight wiring harness is not compatible with the trucks head light electrical system, in the 1999 to 2002 1500 new body style silverado's and sierra's and the 2000 to 2002 2500 and 3500 new body styles GM decided to change the electrical from a positive common to a negative common, so you have grounds where power should be and visa verca.
     
  8. overboost

    overboost Junior Member
    Messages: 5

    so basically i have to scrap the harness that came with the plow for the headlights and make a new harness but that maycause an issue on the headgear because that uses a single common ground as it is onlty a 9 pin harness
     
  9. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    The 2000 GMC you have calls for a 6 relay system with a DRL diode headlight harness, you probably have a two relay headlight harness from the 98, the problem with having the incorrect headlight wiring is on the truck side where the incorrect Fisher harness (although it seems to plug into the vehicle harness very nicely) is not transmitting the electrical signals and current to the proper places in the truck, it's crossing wires. That's why things are messed up. I'm sure if you had a Fisher schematic for the correct harness and a schematic for the harness you have you could reconfigure your present harness to work simply by changing the location of a few wires and that would leave you without having the DRL option to the plow lights, but who needs them on the plow anyways.
     
  10. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    Go to Ebay, item # 271125684434, it is the 2 plug relay type wiring from a 2000 GM truck, it has damage to the control harness which you have already, it's pretty cheap right now, ends tomorrow, you can get the correct headlight wiring system out of this set up.