Jump to content

Third Brake light not working

NYMetsFan86

By NYMetsFan86
in Ask A GM Technician

 Share

Recommended Posts

NYMetsFan86 Enthusiast

NYMetsFan86

Posted
Posted

I was outside my truck while it was running last night ans noticed the third brake light was off. I had someone stand behind it while I hit the brakes, no light. I then had someone stand off to the side while I put it in reverse. Still no light. Should I test the harness? Any ideas? I am now uncertain how long it has been out or how to troubleshoot and find out what the issue is. Thanks

 

2017 silverado LT Crew 4x4

newdude Senior Enthusiast

newdude

Posted
Posted

Warranty. Getting somewhat common on these K2 trucks. All we've seen are blown bulbs and one or two cracked housings like the GMT-900 CHMSL used to do from being over tightened at the factory.

JimCost2014 Senior Enthusiast

JimCost2014

Posted
Posted

I was outside my truck while it was running last night ans noticed the third brake light was off. I had someone stand behind it while I hit the brakes, no light. I then had someone stand off to the side while I put it in reverse. Still no light. Should I test the harness? Any ideas? I am now uncertain how long it has been out or how to troubleshoot and find out what the issue is. Thanks

 

2017 silverado LT Crew 4x4

Check the fuse in the large fuse box in the engine compartment. Had the fuse for the 3rd brake light fail in my 08, had to replace the whole box because you can not fix just one fuse port.

NYMetsFan86 Enthusiast

NYMetsFan86

Posted
  • Author
Posted

Check the fuse in the large fuse box in the engine compartment. Had the fuse for the 3rd brake light fail in my 08, had to replace the whole box because you can not fix just one fuse port.

 

gonna give this a try and see what happens. Will report back, Im guessing if the fuse box went its a warranty replacement but i never want to assume

JimCost2014 Senior Enthusiast

JimCost2014

Posted
Posted

 

gonna give this a try and see what happens. Will report back, Im guessing if the fuse box went its a warranty replacement but i never want to assume

If that is the problem, could not see why it would not be warranted. When the 08 went bad, it actually blew both bulbs, so I replace the 3rd brake light thinking that was it, but when I plugged it in, no power. The dealer was actually the one who found out it was the fuse box not sending power to the light.

NYMetsFan86 Enthusiast

NYMetsFan86

Posted
  • Author
Posted

fuse does not look blown, need to grab a multi tester after work to check the harness. ..I was hoping it was the fuse.

  • 4 years later...

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
 Share
Go to topic listing

  • Latest Articles

  • Posts

    • Coastie05
      It's Been a Long Time...

      By Coastie05 · Posted

      Welcome back!
    • davester
      New to Me 2010 SLE (Quirks, Issues)

      By davester · Posted

      not all plugs will be used.  gm uses more generic harnesses that support most/all options, and if your truck doesn't have a specfiic option, the plug won't be used (commonly will have a dummy insert in the plug , or it'll be taped up, but some may just be left as is).  But it's sldo possible some p.o. has installed the wrong/cheaper parts that aren't correct for your vehicle...
    • fm2176
      New to Me 2010 SLE (Quirks, Issues)

      By fm2176 · Posted

      First off, I'm not trying to just get easy advice/fixes for the issues I've noticed so far.  I'll be combing through the site via searches and such, and if past experiences are any indication, should find what I need.  For the sake of conversation, though, I figured I'd post the handful of things I've noticed in the 12 hours since buying my 2010 SLE CCSB.     Indicator lights: Airbag and TPMS.  The tire pressures aren't reading for any of the wheels, so I'm pretty certain the sensors were either removed, are damaged, or are otherwise inoperable.  I used to mount and balance tires 25 years ago but am pretty much ignorant when it comes to TPMS.  My 2006 didn't have the sensors and this might be the fourth vehicle I've owned that does.     Radio: Rear speakers aren't working.  I removed the driver's side rear door panel and checked the speaker and wiring.  I also removed the sill and b-pillar covers to check the wiring.  A few minutes of Google Fu showed that this is potentially a head unit issue.    Switches: Power mirrors don't turn left/right.  I ordered replacement driver's door switches that should arrive tomorrow.  The windows and locks work but it was only about $20 for all of them.  The driver's side rear window switch lets the window down but won't put it back up.  I think the passenger rear doesn't work at all.  In the coming days/weeks, I'll break out my multimeter to check all of that.   Unknown wiring harness: There's a box attached to the front driver's side of the engine compartment, right where the second battery shelf is located.  There are three plugs, one of which looks like it fits a standard headlight-style bulb (9007 or similar).  It doesn't look like it's plugged into anything.  I'll do some digging and if I don't see anything elsewhere on the site, post some pictures here.   Unknown plugs on brake booster: There are at least two female plugs on the brake booster that aren't being used.  I think it might be a replacement/aftermarket, so maybe those are used for a different application, as there don't seem to be any unplugged harnesses and no indicator lights are on.   Little squeaks when turning: Sounds almost like a bushing around the bed of the truck.  I'll have to pay close attention as I get more familiar with the truck.   Clunk on acceleration: possibly the infamous drivetrain clunk.  My 2006 had it and I'm just not familiar enough with this truck yet to fully grasp what it is.   Anyway, my apologies for the vague and all over the place post.  This truck is new to me, and it's been four years since I drove my 2006.  With 200k miles, I know I'll need to learn this truck quickly to avoid having any major issues, despite being confident it's got much more life to it.  My 2006 had nearly 320k on it when I parked it (nearly 300k of which I put on the truck), and it was still drivable then, though I suspected the head gasket might have blown.  I'd hoped to have that truck back by now, but it's gone forever, as I detailed in my reintroduction thread.  
    • lowrider
      Range RA007 DFM Module

      By lowrider · Posted

      I always drive in Sport mode. With more driving, I am finding the initial response when accelerating is much quicker now🖕 Lou
    • Tyler Gibbs
      2022 2500HD with a new RSI SmartCap

      By Tyler Gibbs · Posted

      Is it an optical illusion in the pic or is the truck really squatting that much horribly?

  • GM-Trucks.com Clubs

  • Popular Contributors

×
×
  • Create New...