Brake Fluid Level Switch

The brake fluid level switch is a float 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 is grounded through a separate ground. 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 close, sending the reference voltage low. When the brake fluid level is high, the float lifts, opening the switch contacts, sending the reference voltage high on the signal circuit to the BCM.

The brake fluid level switch uses an internal 1k ohm resistor in parallel. This enables the BCM to differentiate between a disconnected brake fluid level switch connector and a full level condition.