Anti-Lock Brake Pedal Travel Switch

This system uses a pedal travel switch mounted on the right side of the brake pedal support, near the dump valve adapter bracket to monitor brake pedal travel and send information to the Anti-Lock Brake System (ABS) module through the wiring harness. Switch adjustment is critical to pedal feel during ABS cycling.

The switch is normally closed. When brake pedal travel exceeds the switch
setting during an anti-lock stop, the electronic controller 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 fills with high pressure brake fluid, pushing the brake pedal up until the switch closes. When the switch closes, the pump turns off and the pedal drops with each ABS control cycle until the travel switch re-opens and the pump is turned back on. This minimizes pedal feedback during ABS cycling.

If the pedal travel switch is not adjusted properly or is not electrically
connected, it will cause an incorrect pedal feel during ABS stops. Some problems with the switch or its installation will result in the pump running during an entire ABS stop. The pedal will become very firm, pushing the driver's foot up to an very high position.