Electrical issues?

Tiny
DAKOTAPAYNE
  • MEMBER
  • 2015 CHEVROLET SILVERADO
  • 6.6L
  • V8
  • TURBO
  • 4WD
  • AUTOMATIC
  • 172,000 MILES
No power to right rear break light and blinker all the way back to the under hood fuse box. No power to sunroof and rear sliding window. Also lower dash lights have no power.
Sunday, August 31st, 2025 AT 9:07 PM

13 Replies

Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 54,137 POSTS
So the brake lights are control by the BCM, so I would check the fuses on it. The sun roof is a stand along unit and has its own fuses which I have included in the images below and a guide to help you check the fuses as well.

https://www.2carpros.com/articles/how-to-check-a-car-fuse

The interior lights are run by the BCM as well. Make sure the power is no while checking the fuses. If the fuses are okay on the BCM we need to do a CAN scan, this video will show you how. If the fuses are okay for the sunroof please start a new thread so we can continue. Sorry, we only handle one problem per thread, please post your new question here, you must be logged in.

https://www.2carpros.com/questions/new

Check out the images (below). Let us know how it goes.

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Monday, September 1st, 2025 AT 9:41 AM
Tiny
DAKOTAPAYNE
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  • 6 POSTS
All fuses check good. I’ve checked them three times now. All three of these things happened at the same time. I have also swapped the under hood fuse box due to corrosion and that didn’t fix the issue either.
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Monday, September 1st, 2025 AT 2:46 PM
Tiny
KEN L
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The fuse test also included if the fuse is getting power, are both of them powered while the truck is on? That can tell us a lot. Please go over the guide again.
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Tuesday, September 2nd, 2025 AT 8:04 PM
Tiny
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As already stated fuses are good and have been checked multiple times.
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Wednesday, September 3rd, 2025 AT 10:26 AM
Tiny
KEN L
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So the fuse have 12 power through them, correct?
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Wednesday, September 3rd, 2025 AT 10:26 AM
Tiny
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  • 6 POSTS
There must be some kind of misunderstanding or miss communication. As stated above all fuses have checked good. Power to both sides of the fuses with the truck on. I’m not sure that I am getting power out of my BCM to the fuse box to power the blinker. If I jump the blinker wire to the trailer harness it back feeds the system and all the issues work if I hold my foot on the brake pedal. Back window will open and close sunroof will open and close dash lights will light up. Right rear blinker and brake light will come on.
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Wednesday, September 3rd, 2025 AT 11:21 AM
Tiny
KEN L
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Sorry, I didn't know if they had power, I know the fuses are good. Now we are getting somewhere :) Please check the fuse #8 60 amp in the fuse box near the battery. Top right of the engine compartment. This fuse feeds the systems that are not working. I apologize for the confusion.
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Wednesday, September 3rd, 2025 AT 1:40 PM
Tiny
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Okay, will double check that fuse also I just pulled the codes on the truck with a code B3951-04. Googled that code and it’s saying it’s not a fuse issue?
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Wednesday, September 3rd, 2025 AT 7:04 PM
Tiny
KEN L
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The code B3951-04 is for an open circuit for the right taillight. So this issue popped up all a the same time, correct?
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Thursday, September 4th, 2025 AT 10:17 AM
Tiny
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Yes, I parked the truck for a week for vacation and when I returned all of the issues arose at the same time. I’m starting to think it’s a body control module issue.
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Thursday, September 4th, 2025 AT 11:08 AM
Tiny
KEN L
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Yep, I would say that too for the interior lights and the right rear tail light, but the sunroof and rear slider window do not go through the BCM. I did notice that both the rear slider and sunroof use the SEO RAP fuse in the left side of dash interior fuse panel.
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Thursday, September 4th, 2025 AT 11:28 AM
Tiny
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So the weird thing is if I wire the brake light and blinker into the trailer harness I have power to the sunroof and back glass when I hit the brakes or turn the blinkers on.
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Thursday, September 4th, 2025 AT 11:54 AM
Tiny
KEN L
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Can you see if the the SEO RAP fuse has power with the truck on? It sounds like the lights are back feeding the circuit through the BCM.
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Thursday, September 4th, 2025 AT 6:15 PM

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