Brake lights dont work - 2001 Chevrolet Blazer

Not sure but the last post on this link has some solutions which should not cost anything

https://dodgeforum.com/forum/2nd-gen-dakota/229748-abs-light-and-parking-brake-light-on.html

Check bulbs,fuse.

For starters it is spelled "Brake" light...LOL . Sounbds like you may have a brake light switch that has gone out. In yor owners manual does it show more than one fuse for the brake lights? Most vehicles with a thrid/highmount brake light split the brake light power to either the left and third brake light and the right brake light or vice versa, or posibble 3rd brake light on its own fuse. I would check if all of the brake light including the 3rd brake light dont work. If no lights work at all it leans toward the switch which controls all or them to activate hence the brake light switch. It should be mounted on your brake peal arm or to the main base. The pedal lever activate the switch when you depress the brake pedal.

I'll help with the brake lights. 1st check fuse, 2nd there is a brake light switch located at the brake pedal you will need to get under the dash & find it. Remove plug from switch & bridge plug with wire If the lights come on the switch is faulty (have the ignition on while doing this) 3rd check brake globes it is possible all are blown.

You have a failed brake lamp relay,this is located at the back right hand in the trunk at the quater panel.

That does not make any sense. Do the tail lights work? There are supposed to be separate filaments for brake lights, tail lights, and turn signals. In particular the center brake light should not be possible to be confused with tail lights or signals. Does it come on? If not, then you probably have no brake lights at all, and that is probably because of the bad fuse or the switch on the brake pedal for the brake lights.
If there is some sort of cross over between tail light and brake lights, that is usually from a bad light socket ground; which results in current backing up from one system to another. But then each is usually only half brightness.

The brake lights are routed through the signal light switch.
Looks like that will be the next switch to replace and the problem.

I have a 2001 Ford F150, my brake lights dont work. Ive replaced the bulbs, checked the fuses,and the brake switch on side of the brake pedal was replaced. I still dont have any brake lights. My third brake light works fine, along with my running lights,flashers, blinkers.

check the fuse for the brake lights. The brake lights and siganl lights use the same bulb filament. The parking and running lights use a dimmer filament in the bulb. There are 2 filaments.
Your brake lights work through the multifunction switch which operates the signal lights. If the signal lights work, you may have a bad brake lamp switch which is on your brake pedal arm.
Let us know what you find.

check brake light switch..under dash up at top of brake pedal.with wiring harness on one side and spring loaded pintle on other that reads when brake pedal is applied