3rd BRAKE LIGHT NOT WORKING No power to it 2007 yukon?

2007 GMC YUKON
208,000 MILES • 5.3L • AUTOMATIC
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2007GMCYUKON
3rd brake light out no power .. check fuses all the fuse in both inside and outside boxes just because i was there anyways. Check light with direct power to it lights fine . Check for current to light im getting nothing with brake pressed or not pressed its light blue wire positive and black wire negative. check pigtail wire harness also nothing... Brake lights work perfect blinkers work fine reverse light all good plate lights good also. the 3rd brake light wire runs along the inside drivers side could the brake switch cause this ? also seen someone mention the parking brake switch? another said bcm . I have a pretty good understanding that BCM send a signal to light it up but does it go thru the brake switch or direct ? I know its on its own power source is why everything else works. just stumped on this one any help appreciated dont want to start buying all kinds of parts and still at square one. Thanks guys
Jun 28, 2026 at 5:56 AM
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STRAILER
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I got you covered, yep this problem is pretty straight forward, the BCM or wiring from the BCM is bad. Here is a guide to help you check the wiring if needed to confirm the problem and the wiring diagrams for the center high mount brake light so you can se ehow the system works.

https://www.2carpros.com/articles/how-to-check-wiring/

Check out the images (below). Please upload an image or a short video in your response, so I can see what's going on.
Jun 28, 2026 at 5:26 PM
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STRAILER
  • ASE Certified Mechanic
  • 54,517 POSTS
  • ASE Certified Mechanic
Sorry here is the diagrams,
Jun 28, 2026 at 5:27 PM
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