The starting circuit is activated when the ignition key is in the starting position. At this stage, current passes through the solenoid coil, and the resulting magnetic field moves the solenoid plunger. During its movement, the plunger moves the lever, which in turn engages the starter gear with the flywheel ring gear. At the end of its stroke, the plunger connects the internal electrical contacts, after which all the current from the battery begins to flow to the starter motor, causing it to rotate.
After the engine starts, a one-way clutch on the starter armature shaft allows the pinion to rotate freely on the shaft while being driven by the flywheel. This eliminates the risk of damage to the starter that would occur if the starter were to be driven by the engine. As soon as the ignition key is released from the start position, power to the solenoid coil will cease to flow, and the spring will return the solenoid plunger to its original position. At the same time, the lever will move the starter gear away from the flywheel ring gear. When the solenoid plunger springs away from the electrical contacts, they will open and the starter motor will no longer receive power.