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Headlamp harness '11 GMC

Discussion in 'Fisher Engineering Discussion' started by PLM-1, Dec 29, 2010.

  1. PLM-1

    PLM-1 Senior Member
    Messages: 424

    Having trouble getting the headlamp harness to work correctly on '11 GMC. Which side do the connectors need to be flipped? I've got the low beams on B and the highbeams on A at the moment. I really don't want to take the air cleaner and battery out again if these need to be changed. This is on a Fisher 29400-2.

    Also, what color is the wire for the turn lamps and DRL's? I can't find any schematics for these '11 trucks.

    My '04s headlamps were MUCH easier than these...at least you could take the entire thing out instead of working in a tiny hole with SHORT wires.

    Thanks guys!
     
  2. PLM-1

    PLM-1 Senior Member
    Messages: 424

    To clarify:

    Low beams: i have common on harness to the orange wire on the actual headlamp

    High beams: i have the common to the harness to the yellow wire on the actual headlamp

    Turn signals...i have no idea. Can't even figure out how to get the bulb out, the headlight HAS to come out some how. The manual says to remove air cleaner and do it from behind but there is no way to get the turn bulb out. Look at the harness though it runs over to the side indicator and there are 2 white wires and 1 green. My bet is on the green but don't want to splice and find out later.
     
  3. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    To remove the headlights, first remove the grill which is just in there with a few bolts and some clips... comes right out. The headlight assemblies have two or three bolts on the front side and one bolt on the side which you can access by pulling the first couple screws on the plasic fender liner in the wheel well. Then you can reach in there with a 10mm socket. All you have to do is loosen the bolt, the headlight assy is slotted. Use a test light to confirm which wire is for each directional. Just probe the connector past the weather pak on the backside. There is no wire for DRL's.

    As far as configuration goes, and I'm not sure I'm reading your post correctly, the correct configuration is achieved where the vehicle connectors, which you'll unplug from the headlights, attach to the plug in harness. The COM wire in the plug in harness connector should be oriented with the black wire in the vehicle harness connector on both high and low beam.
     
  4. PLM-1

    PLM-1 Senior Member
    Messages: 424

    Thanks for your reply. That darn grill WILL NOT come out of there. It appears to be snagged on the bumper cover's lip...the entire bumper cover flexes when I tug on it.

    As for the DRL, will I just not have to mess with that wire then? I remember on my '04, the entire headlight system wouldn't work without it.
     
  5. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    Hmmm... I've done a couple 2011's, my own included, but they were Chevys. Possibly something slightly different on that Denali grille. Sorry to make it sound so simple. Not sure what the answer is on the GMC.

    As far as DRL goes... nothing to mess with there.
     
  6. PLM-1

    PLM-1 Senior Member
    Messages: 424

    Went out and took a pic. The grill has tabs that go behind the bumper cover under the headlight.

    INSIDE.jpg
     
  7. PLM-1

    PLM-1 Senior Member
    Messages: 424

    Thanks for your help. The grille on the '04 just popped right off, nothing can ever be simple.

    I'm sure I'm the only moron putting a plow on a Denali HD as well...:eek:
     
  8. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    My chevy is an LTZ... Not as fancy as the Denali, but still a pricey plow truck. :eek:

    Ah... it's still just a truck, and trucks should have plows on them. :D
     
  9. PLM-1

    PLM-1 Senior Member
    Messages: 424

    That's what I tell people, "it's just a freakin' truck". My main deal behind the denali is that I hated the chrome bumpers and I wanted cooled seats.

    On the headlight thing, I've started pulling the inner fender and it looks like i can see the back of the headlight ...still in the process though.
     
  10. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    You're on the right track. Just pull the first couple screws, and you can pull the inner back and get a socket in there. Just loosen the bolt, the headlight is slotted.
     
  11. PLM-1

    PLM-1 Senior Member
    Messages: 424

    Looks like the damn grille still has to come off. There's tabs on the corner of the headlight that keeps it from tilting out!!! Grrr
     
  12. PLM-1

    PLM-1 Senior Member
    Messages: 424

    Finally got it out. You have to pull the upper bumper cover. Now, any idea which wire to tap on the turn signal? There's 2 green, 2 gray and a black. I can't get a test light into them because the wires are so short I'll stab my finger trying to probe it.
     
  13. cubicinches

    cubicinches PlowSite.com Addict
    Messages: 1,412

    Don't stab the wire, just slide the test light inside the weather pak at the back of the connector.
     
  14. PLM-1

    PLM-1 Senior Member
    Messages: 424

    I got it all done. I ended up just poking the wire as my test light wouldn't go up under the connector. I was correct on both wires so I just tapped it where I stabbed it. They're both tan out of the turn/park light on the driver's side. They appeared gray on the passenger side.

    I've got a plow light's low beam on the driver's side that won't illuminate now. When it's plugged in I can see a dimly lit coil in the bulb, but not full illumination. The high beam works fine. I tried flipping the connector over but then the truck headlight didn't work so I'm thinking the connector is property oriented.

    I just went and got new bulb but that didn't fix the problem.