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Brake light problem

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Old Jan 5, 2026 | 07:31 PM
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Default Brake light problem

I have a 2016 CX-5 Touring 2.5L, no custom mods or changes.

The brake light on the driver's side does not work, but the running light (or whatever it's called) does work. The high stop and passenger side work as they should, as do all the other lights.

Naturally, I figured I'd replace the bulb and be good to go, but that did not fix it. I also tried swapping the right and left bulbs in the off chance that the ones I just bought were bad, but still no luck. Fuse is fine, though the right side is on the same circuit, so I wouldn't have expected the fuse to be bad anyway. At this point, I'm figuring either the socket is bad, or the wiring is messed up somehow -- though the socket looks totally fine to me.

Does anyone have any ideas of where I can start looking? Is there maybe a connector somewhere where several "branches" meet and maybe became loose or corroded or something, and if so, any general idea where it's located so I don't have to tear apart the trim trying to find it?

Thank you very much, I appreciate any help!
 
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Old Jan 5, 2026 | 11:56 PM
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Welcome to the forum
 
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Old Jan 6, 2026 | 07:06 AM
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Originally Posted by Callisto
Welcome to the forum
Thank you!
 
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Old Jan 7, 2026 | 04:58 AM
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Do you have 12v & earth at the socket when the brake is applied?
 
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Old Jan 7, 2026 | 09:19 AM
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Talking

Originally Posted by sam9978
I have a 2016 CX-5 Touring 2.5L, no custom mods or changes.

The brake light on the driver's side does not work, but the running light (or whatever it's called) does work. The high stop and passenger side work as they should, as do all the other lights.

Naturally, I figured I'd replace the bulb and be good to go, but that did not fix it. I also tried swapping the right and left bulbs in the off chance that the ones I just bought were bad, but still no luck. Fuse is fine, though the right side is on the same circuit, so I wouldn't have expected the fuse to be bad anyway. At this point, I'm figuring either the socket is bad, or the wiring is messed up somehow -- though the socket looks totally fine to me.

Does anyone have any ideas of where I can start looking? Is there maybe a connector somewhere where several "branches" meet and maybe became loose or corroded or something, and if so, any general idea where it's located so I don't have to tear apart the trim trying to find it?

Thank you very much, I appreciate any help!
I'd like to suggest a trip to a local Mazda Dealer to trade up ( asap ) !
 
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Old Jan 7, 2026 | 10:01 AM
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Originally Posted by Clinic
I'd like to suggest a trip to a local Mazda Dealer to trade up ( asap ) !
Really........... as a new member and your first posting here????
No comment
 
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Old Jan 7, 2026 | 07:50 PM
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Originally Posted by Clinic
I'd like to suggest a trip to a local Mazda Dealer to trade up ( asap ) !
IDK, I hear the 2016 was one of the best years that Mazda made and other than this little issue it's running and looks absolutely great.
 
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Old Jan 7, 2026 | 07:51 PM
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Originally Posted by grim_reaper
Do you have 12v & earth at the socket when the brake is applied?
I'll give that a check on the weekend when I can get someone to help me. Do you know if the brake is the pink/black or red wire? ...or I guess I'll just make sure I'm getting power to both.
 
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Old Jan 8, 2026 | 08:15 AM
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If the power and ground check out...then...
I know it sounds weird, but it is possible for the brake light switch to be faulty and cause only one light to work/not work.
BN7N-66-490A it's about $22 US dollars.

Welcome to the forum
 
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Old Jan 8, 2026 | 01:58 PM
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Originally Posted by Lobstah
If the power and ground check out...then...
I know it sounds weird, but it is possible for the brake light switch to be faulty and cause only one light to work/not work.
BN7N-66-490A it's about $22 US dollars.

Interesting, I never would have thought of that but good to know. For $22 it's worth a try if everything else checks out.


Welcome to the forum
Thank you @Lobstah and thank you for the help!
 
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