What Is a Brake Light Switch?

by Andrea Stein

Cars rely on a number of systems in order to run properly. The breaking system in a car consists of both mechanical and electrical parts used to complete the standard breaking procedure. The brake light switch plays an integral role in this process.


A brake light switch is an electrically powered switch that triggers the brake lights to activate when brakes are applied.


A brake light switch operates via two wires, called a power-in wire and power-out wire. When a driver depresses the brake pedal, a plunger device contacts a metal plate, which completes an electric circuit in the switch via the two wires. The switch then activates the brake lights.


Brake light switches can be used for such applications as cruise control cut off and shift lock trigger. Brake light switches used for cruise control work by transmitting a signal to the car’s computer unit, which then cuts the cruise control to enable deceleration. The brake light switch also sends a signal to the computer when activating shift lock or automatic transmission. Shift lock assures the brake pedal is depressed before allowing the car to shift gears.

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