This starter switch controls the engine cranking circuit in the host tractor's electrical system. It sits between the ignition key cylinder and the starter solenoid, completing the circuit that engages the starter motor. The switch is an original AGCO component, machined to match the mounting bore and electrical connector geometry of the original assembly so no adapter harness or bracket modification is needed. A switch that fails to make clean contact can cause intermittent cranking or a no-start condition. On replacement, verify that the key cylinder rotates freely through all positions before securing the switch in place.