Brake Fluid Level Sensor/Switch: Description and Operation

The master cylinder fluid level sensor, which is a switch located in the side of the reservoir, activates the red "BRAKE" warning lamp on the I/P cluster when the brake fluid level is low. Once the fluid level is corrected, the "BRAKE" warning lamp will go out. A sensor is also in the pressure modulator valve assembly reservoir. When the reservoir fluid level is low, the sensor switch opens, signaling the electronic brake control module (EBCM) to deactivate the ABS and turn on the "ANTILOCK" warning lamp.