Brake Light Switch The brake light switch is a small component near the brake pedal responsible for activating your car's brake lights. How does it work? When you press down on the brake, the brake light switch turns on the brake lights at the rear of your vehicle. Essentially, it lets the driver behind know that you intend to slow down. https://www.theautopartsshop.com/electrical-lighting-and-body/brake-light-switch