How does the starter motor work?

When you turn the ignition key to the "Start"bottom,the battery voltage goes through the Starter motorcontrol circuit and activates the solenoid switch,which in turn energizes the Starter motor.It cranks the engine.

Starter motor can only be operated when the automatic transmission shifter in "Park" or“Neutral”position or if the car has a manual transmission,when the clutch pedal is depressed.

To accomplish this,there is a Neutral safety switch installed at the automatic transmission (or at the clutch pedal).

When the automatic transmission is not the "Park"or "Neutral"(or when the clutch pedal is not depressed),the neutral safety switch is open and the Starter motor relay disconnects the Starter motor control circuit.