* Bulbs: The brake light bulbs themselves are functioning correctly. They haven't burned out, are correctly seated in their sockets, and have good electrical contact.
* Wiring: The wiring from the brake light switch to the brake lights is intact and undamaged. There are no breaks, shorts, or corroded connections in the circuit.
* Brake Light Switch: The brake light switch (located near the brake pedal) is working properly. It's a simple electrical switch that closes the circuit when the brake pedal is depressed, allowing current to flow to the brake lights.
* Fuses: The fuses in the Blazer's fuse box that protect the brake light circuit are not blown.
* Grounding: The brake lights have a good ground connection to the vehicle's chassis. A poor ground can prevent the lights from working.
* Tail Light Assemblies: The wiring within the tail light assemblies themselves is good and the light sockets are properly connected.
If the brake lights *are* working, it means all of these components are functioning as designed. If they *weren't* working, investigating these areas would be the troubleshooting steps.
