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No low beams

Discussion in 'Fisher Engineering Discussion' started by gmcsierra1500, Nov 28, 2006.

  1. gmcsierra1500

    gmcsierra1500 Senior Member
    from CT
    Messages: 150

    I just installed a fisher MM2 RD on my 2000 GMC sierra 1500 I have the 4 port 3 plug wiring system, my problem is i have turn signals, park lamps, and high beams but no low beams, any idea what might be going on, any help would be great, thanks
     
  2. DeereFarmer

    DeereFarmer PlowSite Veteran
    Messages: 3,296

    Is this a brand new plow? I know that on used ones the low beam in the sealed beam light can go out. This happens fairly often, mostly from sitting all summer long I would guess.
     
  3. gmcsierra1500

    gmcsierra1500 Senior Member
    from CT
    Messages: 150

    yes it is used

    Yes it is a used plow along with the light harness, the battery and control harness are new
     
  4. ashsupply

    ashsupply Junior Member
    from nh
    Messages: 26

    what type of truck did this come off of???
     
  5. gmcsierra1500

    gmcsierra1500 Senior Member
    from CT
    Messages: 150

    I dont know what the plow came off of, the seller had multiple used plows and truck side setups and he said the wiring harness would work
     
  6. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    The lows have never worked on your truck, correcet?

    Pull the wires off the plow's headlamps and run a voltage check across the terminals to see if you're getting power to the low beams at all. If so then you've probably just got a pair of bad lamps...go buy a pair and see if that fises it.

    Otherwise go back to the area behind your truck's headlights and double check your wiring. I'm guessing since you're without low beams only that you may just not have the wires on correctly. I know when I hooked mine up (see sig, very similar setup to yours) last month that the headlight wiring instructions were vague at best in the Fisher instalaltion manual and I had to guess which was for the low beam and which was for the high beam.

    If it'll help I can go out to my truck and check the wire colors on my harnesses behind the headlamps and tell you which color wires I have going to my lows from the ISO module.
     
  7. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    For what its worth, I just ran outside. I can post crappy ohone pictures if you like. Here is how mine is wired up:

    - From the ISO module the female plug with the yellow wire is mated to the male plug from the truck's wiring harness with the yellow wire.
    - On the other side if the Fisher harness the male plug with the orange wire goes to the low beam and the male plug with the red wire goes to the high beam.
    - Colors repeated on the passenger side of my setup.

    None of the color codes were in the install manuals I got off the Fisher website. I took a shot and guessed on the yellow wires matching up and used a multimeter to check for voltages to determine which one was low bean and which one was high beam.

    Hope this helps.
     
  8. Nascar24

    Nascar24 Senior Member
    Messages: 645

    Hi

    I had a similiar problem with my used harness last year on My Ford, I found on the Fisher tech pages a spot where there is a small pig tail with a jumper plug, I had to switch the jumper wire around, worked fine after that.


    Heres a link to Fishers mechanics guide page 12 of 70 it's the configuration plug on the #1 harness http://www.fisherplows.com/pdf/27179_070001.pdf


    Jay
     
    Last edited: Nov 29, 2006
  9. gmcsierra1500

    gmcsierra1500 Senior Member
    from CT
    Messages: 150

    With the 1999-2002 New sierras the configuration plug is not needed
     
  10. gmcsierra1500

    gmcsierra1500 Senior Member
    from CT
    Messages: 150

    update

    Heres where i am at now, all the lights on the truck work, the high beams, park lamps and turn signals on the plow still work, but still no low beams, i pluged my lamps into my buddies plow and found out the the lamps do work so its not my plow lights, when i put my electrical tester to pin # 7 on my 11 pin truck side harness the low beams on the truck shut off and the tester lights up, are my wires crossed heading to my headlights, the harness came with a plug side to the low beams and high beams on the truck, and also to the low beams and high beam plugs on the original truck lighting harness.
     
  11. gmcsierra1500

    gmcsierra1500 Senior Member
    from CT
    Messages: 150

    Still no luck

    Can any one tell me what pin positions they have power to on your lighting harness were it connects to the plow? i have power to 11, 5, and 7, and when i put my tester to 7 my low beams on the truck shut off.
     
  12. mayhem

    mayhem PlowSite.com Addict
    from Peru MA
    Messages: 1,016

    I'd be happy to check mine when I go home tonight. Just to clarify, you're talking about the harness thats coming out of the grill and plugs into the actual plowside harness, correct?

    Did you pull the headlights out and recheck your plugs there to make sure you have them matched correctly?

    I would also pull each plug one at a time to make sure you don't have any bent pins...this includes right back to the ISO module. All you need is for one lousy bent pin to not make contact and you're toast.
     
  13. gmcsierra1500

    gmcsierra1500 Senior Member
    from CT
    Messages: 150

    Yes i am talking about were the truckside harness plugs into the plow, i checked all the pins and connections and everything seems to be right
     
  14. cheesycoolguy

    cheesycoolguy Junior Member
    Messages: 9

    I had the same probalem with mine. On mine there is a jumper in the same area where the fuses for the plow wiring are. Just switch the side the wire jumps to leaving one end of the jumper in the center pin. I don't know what this does but it worked for me. I think they call it a control chip.
     
  15. gmcsierra1500

    gmcsierra1500 Senior Member
    from CT
    Messages: 150

    thanks

    Thak you everyone for you help, i found out i had the wrong headlight harnesses, so since i have changed those out everything seems to be working fine now, hopefully well get enough snow tonight to try it out!