Brake Fluid Level Switch

For vehicles equipped with a vacuum brake booster, the brake fluid level switch is hardwired to the BCM through a single signal circuit and grounded to a body ground through a separate circuit. The BCM provides a reference voltage to the brake fluid level switch. When the brake fluid level is low the switch closes, pulling the reference voltage low. When the brake fluid level is high, the switch opens, sending the reference voltage high on the signal circuit to the BCM.

For vehicles equipped with EBB, the brake fluid level switch is mounted in the master cylinder reservoir and is hardwired to the ABS module through a single signal circuit and is grounded through a separate return circuit. The ABS module provides a reference voltage to the brake fluid level switch. When the brake fluid level is low the switch closes, pulling the reference voltage low. When the brake fluid level is high, the switch opens, sending the reference voltage high on the signal circuit to the ABS module.