This differential lock switch completes the electrical circuit that engages the differential lock mechanism on the host tractor. It mounts in the operator station and sends a signal to the solenoid or actuator that physically locks the differential, forcing both drive wheels to turn together. A failed switch prevents lock engagement, which can cause wheel slip in soft soil or reduce traction during heavy drawbar work. The switch contacts and internal spring are designed to match the original assembly's actuation force and travel, so the lock engages and disengages with the same pedal feel as the factory system. On replacement, verify the connector seats fully and the switch bracket is not bent.