Because something's wrong, of course. What it could be... bad switch, break/short in the wiring, bad fuse or relay, or even just bad bulbs.. chances are, your car uses dual filament bulbs for the brake lights, where they'll function as both marker lights (with one filament active) and brake lights (with both filaments energized).
applying the brakes
faulty master brake system
A disc brake squeal can occur even when not applying the brakes due to vibrations between the brake pads and rotor, which can be caused by factors like uneven wear, contamination, or improper installation.
You use them by applying the brakes.
STICKING BRAKE CALIPER
by applying the brakes on full
Check the switch at the brake pedal .
The squealing noise from your bike's disc brake when not applying the brakes could be due to contamination on the brake pads or rotor, misalignment of the brake caliper, or worn brake components. It is recommended to clean the brake pads and rotor, check for any misalignment, and inspect the brake components for wear to resolve the issue.
it may need some brake fluid
Is the brake fluid level low in your brake master cylinder in the engine compartment ?
brake lights say lit after ignition has been shut off. lights shut off after hitting the brakes.
My rear window brake light works, but not my tail light brakes on my 1997 Monte Carlo. What is the problem?