The ignition coil steps up the 12 volts available from the battery or alternator to a voltage of 30,000 or more volts at the spark plug. Converting a lower voltage input into a higher voltage output makes the ignition coil a step-up transformer.

The firing order of the cylinders in an engine is different than the cynlinder numbers and can be found by observing the order in which the intake valves open.

The battery supplies the power necessary to start the engine when the ignition switch is is turned on.

The master (brake) cylinder converts pressure on the brake pedal to hydraulic pressure in the brake lines.

Sensors provide the data necessary for the vehicle's computer to make decisions and monitor everything from simple vehicle information like tire pressure to complexities like the chemical content of an engine's exhaust.