How do cars shut off?

Answer 1

For those who don't know anything about ignition systems, heres a little insight on the subject: A basic ignition system consists of an ignition switch, ignition coil & distributor assembly or computer & coil packs, spark plug wires, and spark plugs. When the ignition switch is on, a 12 volt power supply runs to an ignition coil which amplifies the voltage to as high as 30,000 volts. The current then runs through a distributor assembly which directs and delivers the power supply in segments to the spark plugs through wires. The spark plugs "fire" which ignites the air/fuel mixture in the engines corresponding combustion chamber causing the reaction that produces the engines power. Vehicles with coil packs have the 12 volt power supply run through a computer which does the same thing as a distributor before sending the current through the coil packs and then to the spark plugs. When you turn off the vehicle, mechanical linkage running from the ignition key cylinder assembly separates two sections of the ignition switch that severs the 12 volt supply current to the rest of the vehicles ignition system, thereby disabling the ignition spark, stopping the combustion reactions, and stopping the engine.