F 150 Super Crew 4WD V8-5.4L Prop SOHC VIN Z (2003)
Brake Fluid Level Sensor/Switch: Description and Operation
Warning Switch, Brake Fluid Level
The brake master cylinder fluid level warning switch is an integral part of the brake master cylinder reservoir. It consists of a float containing a magnet
and a reed switch mounted in the bottom of the brake master cylinder reservoir.
When the brake fluid in the brake master cylinder reservoir gets to a predetermined level, the floating magnet actuates the reed switch, causing the red
brake warning indicator to illuminate. Loss of brake fluid from either the primary (front) hydraulic circuit or secondary (rear) hydraulic circuit will
cause the warning indicator to activate. If the brake fluid level warning switch is inoperative, the brake master cylinder reservoir must be installed
new.