What is a Parking Brake Activation Switch?
Electronically activated parking brakes are becoming more common, especially from manufacturers of luxury vehicles. These systems do not use the regular pressed, pulled, or lifted manual actuators, they are engaged by a button that typically has a 'P' with a circle, or some other designation for the parking brake. When the button is pressed, the parking brake is set. In most cases, the parking brake is released by either pressing the button again, or by moving the button in a different direction.
How do Parking Brake Activation Switches work?
When the parking brake button is pressed, it sends a signal through a wire to the parking brake control module. This control module will determine the meaning of the incoming signal, and then output a signal to the parking brake control motor to set the parking brakes. Once the parking brakes are set, the brake rotors will be locked in position so the tires will be unable to move. Next, when the driver would like to move the vehicle, the parking brake release function is used, and that sends an opposing signal to the parking brake control module. The parking brake control module, again, interprets the signal, and signals the parking brake control motor to release the parking brakes. The rotors are now free to move, and the wheels and tires can rotate freely.
What are the symptoms of a bad Parking Brake Activation Switch?
Only three symptoms are possible of the parking brake switch. The parking brake switch may fail to engage the parking brake. This would be because the parking brake control module never gets the signal to set the brakes. Next, the parking brake switch may fail to release the brake, if the activation switch doubles as the deactivation switch. Finally, erratic operation of the parking brake switch when not pressed may occur, so warning messages would appear on the instrument cluster if the switch requests the parking brake while driving.