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No low beam on passenger side

Discussion in 'Fisher Engineering Discussion' started by jwoodell, Nov 14, 2010.

  1. jwoodell

    jwoodell Junior Member
    Messages: 4

    I have an 8' HD MM2. It was previously installed on my '03 GMC 2500HD. I traded that truck and transferred everything to my '08 GMC 3500HD which required changing the low beam connectors on the harness. Everything works fine except the passenger side low beam on the plow. The wiring checks out from the isolation module to the light, it just appears that the isolation module isn't sending any voltage to the light. Am I overlooking something here or do I have a bad isolation module?
     
  2. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    Is there a configuration plug on the control harness? Does the 08 installation call for one?
     
  3. jwoodell

    jwoodell Junior Member
    Messages: 4

    Yes, there is a configuration plug. It just has a dust cap on it. I tried a jumper from B to A that didn't change anything. I don't know if the '08 requires one, where would I find that info? Also, the PS low beam does have power when the high beam is on. Both DS and PS have both beams on when high beam is on.
     
    Last edited: Nov 14, 2010
  4. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    I can't find anything that says the H11's need the config plug, Can you flip the low beam connector 180 degrees and plug it back in and try it, I am not familiar with the connector changing but the new GM wiring (3port iso) has the flip plug to allow use in negative common and positve common systems. Are the low beam connectors you changed to a plug and play adapter or did you do some wiring? When you say the wiring "checks out from the iso mod to the plug" did you check it with a test light for power.
     
  5. jwoodell

    jwoodell Junior Member
    Messages: 4

    OK, flipping the low beam connector on the truck 180 did the trick! (I'm glad it was the passenger side, the driver side requires major surgery to access) Thanks.

    To answer your questions though, I changed the low beam connectors by cutting the old ones off and butt splicing new connectors on. I checked out all the wiring using an ohmmeter...it read .02 ohms from iso mod to the plow headlamp plug. Once again, thanks for the assist.
     
  6. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    You're welcome, glad i could help.
     
  7. chachi

    chachi Junior Member
    from NY
    Messages: 16

    what exactly did you flip? the plug from the stock wiring into the headlamp? I'm having a very similar problem on a driver's side low beam.
     
  8. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    What kind of truck? Make, model, year? What wiring setup do you have? 3 or 4 port module? Where did wiring come from if new install on your truck?
     
  9. chachi

    chachi Junior Member
    from NY
    Messages: 16

    I just posted a brand new thread with all the details of my set-up and what I've done.
     
  10. jwoodell

    jwoodell Junior Member
    Messages: 4

    I flipped the connection between the stock wiring and the plow harness.