A brake pedal position sensor is a device that detects the movement of the brake pedal in a vehicle. It is attached to the brake pedal lever underneath the dashboard.
One job of the sensor is to turn on the brake lights to alert drivers to the rear of the vehicle whenever the driver presses the brake pedal. A brake light is necessary in order to comply with federal law. But, unlike a simple brake light switch (that does the same thing), the brake pedal position sensor also disengages the cruise control when the brakes are engaged. This is to ensure that the engine does not continue to propel the vehicle forward against the braking system. And, on some hybrid and electric vehicles, the brake pedal position sensor also serves as part of the regenerative braking system.
The symptoms of a failing brake pedal position sensor can be similar to those of a bad brake light switch. Because the sensor is tied to more functions than a brake light switch, it might be more likely diagnosed with a scan tool, especially on hybrid or electric vehicles.
Signs of a bad brake pedal position sensor include: