Your car is equipped with a parking brake that helps prevent the car from rolling when parked on a slope. This is a separate system from your primary brakes, and you must manually engage and disengage it each time. Because you can cause serious damage to the system if you try to drive with the parking brake still engaged, your car is also equipped with a parking brake warning switch and light.
When you engage the parking brake, you should see the Parking Brake light come on in the dash. This is your warning that the brake is engaged and must be manually disengaged before you can drive. In some cars, the light will come on but a buzzer will also sound if you put the car into gear with the parking brake on. The parking brake warning switch is responsible for turning on the light and sounding the buzzer.
The parking brake warning switch is only used when the parking brake is engaged. It is not used when you press the brake pedal or under normal stopping conditions. In theory, it should last for the life of the vehicle, but these switches can and do fail early. If this happens, you may not see the warning indicator on the dash that tells you the parking brake is engaged and you may not hear the warning buzzer when you put the transmission in gear.
The parking brake warning switch is electronic, and like all switches, it’s subject to normal wear and tear. There is also the chance for wiring damage, or even issues caused by moisture in the system that affect the warning light on the dash.
Obviously, driving with the parking brake engaged is a dangerous thing – it will put significant wear on the parking brake system, or even damage the shoes and drum. That means it’s important that you know a few signs to watch for that indicate the parking brake warning switch is beginning to fail. These include:
The Parking Brake Warning Light does not come on when the brake is engaged
The Parking Brake Warning Light does not go out when you disengage the system
The Parking Brake warning light flickers or turns on and off (indicating a short somewhere in the wiring)
Have a professional mechanic inspect and replace the parking brake warning switch so that no further problems arise in the future.