Brake Fluid Level Sensor/Switch: Description and Operation

The brake system indicator light comes on to alert the driver that the parking brake is applied, or that the brake fluid level is low. It also comes on as a bulb test when the engine is cranked.

Brake Fluid Level
With the ignition switch in ON (II) or START (III), voltage is applied through fuse 25 to the brake system light. If the brake fluid level is low, the brake fluid level switch closes, providing ground to the circuit. The brake system light then comes on, alerting the driver to a low brake fluid level in the brake master cylinder. (Check brake pad wear before you add fluid).