Brake Fluid Pressure Sensor/Switch: Description and Operation

When a failure occurs in either the front or rear brake line, the differential switch, detecting a pressure difference in the brake line, turns ON the brake warning light in the combination meter.
Antilock Brake System (ABS) will be disabled and the ABS warning light is turned ON. After the brake system is repaired, depressing the brake pedal will apply pressure to set the switch automatically (at OFF position).