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No Headlights on Plow

Discussion in 'Fisher Engineering Discussion' started by avc8130, Nov 14, 2010.

  1. avc8130

    avc8130 Member
    Messages: 43

    I just installed my X-Blade on my 06 Chevy 2500. Everything seems to work perfectly except the plow headlights never come on.

    The truck headlights work if the plow isn't connected. The high beams work on plow. If I switch the high/low wiring the high beams on the plow come on all the time.

    It seems like the low beams on the plow just don't work. They worked on a different truck 5 minutes before though.

    Suggestions?
    ac
     
  2. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    headlights

    Is it a four port or three port isolation module setup?
     
  3. avc8130

    avc8130 Member
    Messages: 43

    4 port. Green label. Empty configuration plug.
    ac
     
  4. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    Got a friend who will let you swap iso mods to check it out?
     
  5. avc8130

    avc8130 Member
    Messages: 43

    I'm not sure. One buddy has a Fisher but I am not sure what iso box he has. Is that how diagnostics are done on these systems? Swapping parts? Is there no procedure to follow to diagnose issues with a meter or something?
    ac
     
  6. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    A simple test light will tell you if you have power to specific areas. Have you put a test light to the pins on the low beam plugs? Did you buy the wiring used or new? If used What model year truck was it previously used on? What are the part numbers on the two headlight harnesses(#3port and #4 port)? They should be 26351 and 26352. And yes the easiest and cheapest way to diagnose iso-mods and controllers is by using known good ones, you could have a Fisher tech with an iso-mod tester check out your box but there goes a cheap fix out the window, I am not convinced it's the box anyways, I was just trying to eliminate possibilities.
     
  7. avc8130

    avc8130 Member
    Messages: 43

    I don't have the truck at work with me today. I will check part numbers when I get home. I will also pull the headlight covers and check for power with the plow hooked up and lights "on".

    I bought the harness used. It was on a 2004 2500.

    Thanks for the help!
    Ac
     
  8. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    Low Beams

    Those years are compatible, keep us posted with the harness #'s.
     
  9. avc8130

    avc8130 Member
    Messages: 43

    Well I have the following:
    Plug 3: 26291
    Plug 4: 26290

    I guess I have the wrong harnesses?
    Ac
     
  10. avc8130

    avc8130 Member
    Messages: 43

    False alarm. Sent the wife to check again. She came back with "service part numbers" this time: 26351 and 26352.

    Back to the drawing board.
     
  11. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    low beams

    Check your numbers, I think you have 26360 and 26361, if that's the case you could convert them or get the correct ones. Let me know if my numbers are right or if yours are right.
     
  12. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    Alright, go to www.fishersnowplows.com , in the upper right hand corner click on e-search, then in the "search for" box that comes up type in 27179, click on the straight blade insta-act w/ e-force iso-mod guide and go to page fifty and start with the headlight troubleshooting and tests there. Let us know what you find. BTW all fuses are good right (vehicle and control harness). You may have to type the website name in to avoid that default page that comes up.
     
  13. avc8130

    avc8130 Member
    Messages: 43

    I found the guide you are referring to. How do I know if I have positive or negative common?
    Ac
     
  14. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    You have negative common, 1999 to 2002 new body style GM trucks have positive common, make sure your pink splice wire for the DRL's is connected properly, it's on the same circut, don't know if it could cause this problem though. Do the daytime running lights work properly? e-brake off and in drive the low beams should come on.
     
  15. avc8130

    avc8130 Member
    Messages: 43

    I don't have the pink wire hooked up on advice from everyone I have spoken to. They say the lights bounce off the plow and blind the operator. I have the bulbs out on the truck side so they don't blind me. Does the iso mod NEED drl signal? Everyone else said they drive with ebrake on one click to keep the drls off.
    Ac
     
  16. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    DRL's may have nothing to do with the problem, they never bothered me at all either.
     
  17. avc8130

    avc8130 Member
    Messages: 43

    Played with it a bit following the diagnostic chart. I also had the luxury of another Fisher truck there.

    1st I hooked up the other truck to my plow. Headlights work just fine. Plowside = check.

    Next I checked continuity on my #2 harness. Everything seemed fine there.

    So finally I took the dreaded pink wire and touched it to 12v source. This lit EVERYTHING up. Both the truck and the plow headlights.

    Now I am stuck.
    ac
     
  18. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    Well yes you put power to it so it should light up, don't let that mess you up, what kind of truck did you use to test your plow with? If its a chevy with a yellow or green label 4 port module swap it out to see what happens.
     
  19. avc8130

    avc8130 Member
    Messages: 43

    Wait, if the pink wire gets 12v (like it would any time the DRLs are on) it SHOULD light up both the truck and plow low beams? That doesn't make any sense. I thought it was supposed to run the low beams on the plow only at a reduced output when DRLs were "on" on the truck. Then if low beams were "on" on the truck side they would show on the plow only.

    The "spare" truck was a Ford and uses a different 4 port isolation module.
    ac
     
    Last edited: Nov 15, 2010
  20. buddymanzpop

    buddymanzpop Senior Member
    Messages: 601

    You've got a good one going here, hook up the DRL lights like they should be and see what happens.