The term “ignition switch” refers to the lock cylinder portion of a car’s ignition system and is an essential part of the ignition system. The switch is connected to the car’s battery and when it is activated uses the battery power to jump the starter which turns on the engine. Ignition switches are traditionally controlled by keys, however the past decade has seen an increase in the number of cars that use push-button ignition switches.
The battery operated ignition system, where the ignition switch is utilized, replaced the magneto ignition system when electric starting became widely used in the auto industry at the beginning of the twentieth century. The magneto system, also referred to as the “hit or miss” ignition system, required users to activate the starter by turning a crank on the exterior of the vehicle. Magnetos were used on early cars, such as Ford’s 1908 Model T, however by 1910 Cadillac was using a battery operated ignition system in their vehicles. Battery operated systems were referred to Kettering Systems, named for their inventor, and quickly monopolized auto engine design due to their reliability and inexpensive production cost.
The ignition switch is the starting point for the entire ignition system. When an ignition switch is activated, the starter is tripped and sends an electric surge from the battery that crosses through a double wire coil and returns to the battery, creating a magnetic field within the engine. A shift in the gear box throws a breaker in the outer wire of the coil, destroying the magnetic field and transferring the amplified energy into the coil’s inner wire, which in turn rotates the engine and compresses the cylinder’s pistons. Without the initial flip of the ignition switch, the process would not work.
Ignition switches commonly have the ability to control all the power management of the vehicle. Most ignition switches have four modes: off, on, accessories, and start. When the ignition switch is in the “off” position, the engine is not running and no power is being supplied to any other system. When the ignition switch is turned to its “accessory” state, power is channeled from the battery to the non-engine electric systems in the car, such as the stereo, power windows, and power seat adjustments. When the ignition switch is set to the “on” position, it is supplying power to the entire engine and accessories system, and when the switch is flipped into the “start” position it activates the starter.
In most modern vehicles, ignition switches are placed on the right side of the steering wheel column. However, variations in foreign car design, particularly in the late 1980s and early 1990s at time placed the ignition switch in the center console of the front seat near the emergency break. Some modern Saab models still employ this design.
Keys fitted for car ignition systems typically also have the ability to open the car’s door locks, glove box lock and trunk lock. It is customary for the ignition switch keys to be labeled with the car manufacturer’s logo and the shape, size and functionality features of the key varies depending on the company.