Braking Sensor/Switch: Description and Operation

The pedal travel switch monitors brake pedal travel and sends this information to the ABS module through the wire harness. The switch adjustment is critical to brake pedal feel during ABS cycling.

The switch is located in the vacuum booster and can be serviced separately.

The switch is normally closed. When brake pedal travel exceeds the switch setting during an anti-lock stop, the ABS module senses the switch is open and grounds the pump motor relay coil. This energizes the relay and turns the pump motor on. When the pump motor is running, the master cylinder is filled with high pressure brake fluid. The brake pedal will be pushed up until the switch closes. The pump then turns off and the pedal will drop some with each ABS control cycle until the travel switch opens again and the pump is turned on again. This minimizes pedal feedback during ABS cycling.