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low beam relay location?

Discussion in 'Truck & Equipment Repair' started by terrapro, Dec 16, 2008.

  1. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    does anyone know where the relay is for the lowbeams on a 1990 GMC 2500 is?

    my lowbeams dont work and im trying to pinpoint the prob.

    thanks in advance
     
  2. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    No headlight relays on a '90. They're still the old simple style, you have a dimmer and a headlight switch and not much else. :D

    Best place to start is at the dimmer switch with a test light. Brown (or) tan wire on dimmer switch is your low beams.


    If it has a plow on it then it'll be likely that the plow wiring has something to do with the lack of lights. It usually does.
     
  3. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    that is not what i wanted to hear. i have been in and out of the wiring for the plow and under the dash. hoping there was a relay somewhere i missed that was the problem.

    i had this happen to the same year truck a couple years ago and it was the switch which i replaced it and it fixed the problem so that was the first thing i checked but it didnt fix the problem this time
     
  4. REAPER

    REAPER 2000 Club Member
    from 60050
    Messages: 2,228

    Make sure the low beams are not burnt out.

    I hit a curb last year and it blew both my low beam filaments but left me with high beams.

    Just a thought.
     
  5. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    unfortunatly the bulbs are fine
     
  6. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    im actually going to go pick up another switch to try again and cross my fingers the first one is faulty.
     
  7. MAR4CARS

    MAR4CARS Senior Member
    Messages: 246

    If this scematic is correct the yellow wire on the headlamp switch is the low beam out put turn switch on and test yellow wire for 12v if theres 12v with switch on and nothing with switch off the switch is fine. If no 12v make sure the switch feed wire is bringing 12v to the switch i dont have that color wire for you.If the yellow wire is fine then the problem will either be the dimmer switch on the steering column or something under the hood truck wiring,plow wiring plow relay or ground issue.
     
  8. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    i just reread your post B&B, i guess it didnt click at first but you are saying the dimmer switch might be bad? your talking about the dial that controls the dome and dash lights? i never tested that. what would that have to do with the headlights?
     
  9. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    No not the rotary dial on the dash....I'm referring to the actual headlight dimmer switch on the side if the steering column, which I assume is what your now referring to that you changed already?
     
  10. no lead

    no lead PlowSite.com Addict
    Messages: 1,308

    on the plow or the truck?
     
  11. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    no i changed the switch for the headlights not the hi/low switch which i guess i now know is called the dimmer. :eek:

    so how do i go about changing it out? does the cover pop off or do i have to start with the steering wheel puller.

    thanks B&B
     
  12. B&B

    B&B PlowSite Fanatic
    Messages: 12,777

    No need to disassemble the steering column to replace the dimmer switch as it's located about half way down on the exterior of the left side of the column and is remotely actuated by a rod that travels down from the turn signal lever. If you pull the lower dash panel down you can access it. Will have a yellow, a tan, and a light green wire on it.


    But check it (on the tan wire) with a test light like I mentioned before just replacing it, as you don't even know if thats where your issue yet lies.
     
  13. terrapro

    terrapro PlowSite Veteran
    from MI
    Messages: 3,878

    wow, great! ill get that checked out today. i think the switch was like $9 too, cheap fix if thats the prob :bluebounc