The sensor has an input port for measuring hydraulic brake pressure and an electrical connector output for the wire connection that powers the warning light. Some brake failures do not cause the sensor to jump into failure mode.
Brake fluid pressure sensors are used in anti-lock braking systems (ABS). The ABS fault light comes on due to unexpected wheel lock by the ABS system, but may also include insufficient fluid in the fuel tank.
The new Accident Avoidance Technology system also uses a brake fluid pressure sensor.
Many large heavy-duty vehicles, such as trucks, especially those with multiple trailers, use air brakes with air pressure sensors.
Please see the image below：
Brake Problems
The fault could be insufficient hydraulic oil, insufficient brake fluid in the tank, damaged hydraulic lines, or damaged brake master cylinder. This sensor is used to detect differential pressure in hydraulic systems. If the car alerts a hydraulic system failure and the system checks are done, the sensor itself may have failed.
Please watch the following video introduction（Video from Automobile basic ideas）：