If your vehicle is showing brake lights do not come on when pressing the pedal, here are the most likely causes and the parts you'll need to fix each one.
The mechanical switch located behind the brake pedal can wear out or fail internally over time, preventing the electrical signal from reaching the brake lights when the pedal is depressed.
It is surprisingly common for one bulb to burn out unnoticed, followed eventually by the others. This results in a sudden realization that no brake lights are working at all.
A power surge, aging fuse, or a short circuit somewhere in the wiring can blow the dedicated fuse for the brake light circuit, instantly cutting power to all brake lamps.
If the brake light switch was recently replaced or the pedal assembly was worked on, the switch may be improperly adjusted or seated, failing to trigger when the pedal moves.
Corroded wiring, a damaged harness, or a poor ground connection in the rear of the vehicle can prevent electrical current from reaching the light assemblies.