Brake Fluid Level Switch

The brake fluid level switch is a reed type switch that is mounted in the master cylinder reservoir. The brake fluid level switch is hardwired to the BCM through a signal circuit and grounded through a separate body ground circuit. The BCM provides a reference voltage to the brake fluid level switch. When the brake fluid level is low, the float drops, allowing the reed switch to open, sending the reference voltage high. When the brake fluid level is high, the float lifts, closing the switch contacts, providing a ground and pulling the reference voltage low on the signal circuit to the BCM.