Brake Fluid Level Sensor/Switch: Description and Operation

The brake warning light goes on to alert the driver that the parking brake is applied or that the brake fluid level is low. It also lights as a bulb test when the engine is cranked.

Brake Fluid Level
With the ignition switch in ON or START, battery voltage is applied from fuse 10 to the brake warning light.
If the brake fluid level is low, the brake fluid level switch closes and ground is provided to the circuit. The brake warning light lights to warn the driver of low brake fluid level in the brake master cylinder. (Note: Check brake pad wear before adding fluid.)

Bulb Check
With the ignition switch in ON or START, battery voltage is applied to the brake warning light from fuse 10. The generator will provide ground to the circuit until the engine is running. The brake warning light goes on to test the brake warning light bulb and then goes off.