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Q: Brake lights not working in a 2002 Chevrolet Trailblazer

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The brake lights on my SUV aren't working, but the one in the middle does. All the other lights are working fine. I checked fuse 12 and 34, and those are fine. The bulbs are still good. I did some research, and there is a brake switch located on the brake pedal. Is that linked to the brake lights directly? Is it possible for the switch to go bad? Anything else that might cause my main brake lights not to work?

A: Looking at the wiring diagram for your vehi...

Looking at the wiring diagram for your vehicle, I see that all the brake lights share a common ground. They also all utilize the brake lamp switch, so both of these items can be ruled out. The only thing the third brake light does not share with the other brake lights is the #16 vehicle CHMSL fuse. Since you said the third brake light bulb is good, I would check this fuse. If there isn’t a problem with the fuse, then there is a problem with the third brake light wiring. Electrical diagnosis can be difficult, so I suggest you have a trained professional inspect your vehicle’s brake light problem firsthand.

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