Starter Motor: Description and Operation

The starter motor is a 12-volt unit that has the starter solenoid mounted on the drive end housing.
^ The motor is energized when the starter solenoid contacts are closed.
^ This engages the starter drive with the flywheel ring gear and starts the engine.
^ An overrunning clutch in the starter drive protects the starter motor from excessive speed when the engine starts.
^ The current flows through the solenoid pull-in coil until the solenoid plunger is at the end of its travel.
^ The plunger then closes a set of contacts that bypass the pull-in coil, letting the hold-in coil keep the starter drive engaged and passing starting current to the starter motor.