An ignition switch, starter switch or start switch is a

switch In electrical engineering, a switch is an electrical component that can disconnect or connect the conducting path in an electrical circuit, interrupting the electric current or diverting it from one conductor to another. The most common type o ...

in the control system of a

motor vehicle A motor vehicle, also known as a motorized vehicle, automotive vehicle, automobile, or road vehicle, is a self-propelled land vehicle, commonly wheeled, that does not operate on railway track, rails (such as trains or trams), does not fly (such ...

that activates the main electrical systems for the vehicle, including "accessories" (radio, power windows, etc.). In vehicles powered by

internal combustion engine An internal combustion engine (ICE or IC engine) is a heat engine in which the combustion of a fuel occurs with an oxidizer (usually air) in a combustion chamber that is an integral part of the working fluid flow circuit. In an internal comb ...

s, the switch provides power to the

starter solenoid A starter solenoid is an electromagnet which is actuated to engage the starter motor of an internal combustion engine. It is normally attached directly to the starter motor which it controls. The device serves two functions. The first is as t ...

and the

ignition system Ignition systems are used by heat engines to initiate combustion by igniting the fuel-air mixture. In a spark ignition versions of the internal combustion engine (such as petrol engines), the ignition system creates a spark to ignite the fuel-ai ...

components (including the

engine control unit An engine control unit (ECU), also called an engine control module (ECM), is a device that controls various subsystems of an internal combustion engine. Systems commonly controlled by an ECU include the fuel injection and ignition systems. The ...

and

ignition coil An ignition coil is used in the ignition system of a spark-ignition engine to transform the battery voltage to the much higher voltages required to operate the spark plug(s). The spark plugs then use this burst of high-voltage electricity to ig ...

), and is frequently combined with the starter switch which activates the

starter motor A starter (also self-starter, cranking motor, or starter motor) is a device used to rotate (crank) an internal-combustion engine so as to initiate the engine's operation under its own power. Starters can be electric, pneumatic, or hydraulic. T ...

. Historically, ignition switches were key switches that requires the proper key to be inserted in order for the switch functions to be unlocked. These mechanical switches remain common in modern vehicles, further combined with an

immobiliser An immobiliser or immobilizer is an electronic security device fitted to a motor vehicle that prevents the engine from being started unless the correct key (transponder or smart key) is present. This prevents the vehicle from being "Hotwiring ...

to only activate the switch functions when a

transponder In telecommunications, a transponder is a device that, upon receiving a signal, emits a different signal in response. The term is a blend of ''transmitter'' and ''responder''. In air navigation or radio frequency identification, a flight trans ...

signal in the key is detected. However, many new vehicles have been equipped with so-called "keyless" systems, which replace the key switch with a push button that also requires a transponder signal. The ignition locking system may be sometimes bypassed by disconnecting the wiring to the switch and manipulating it directly; this is known as hotwiring. Ignition switches are generally a simple repair that can be completed without much knowledge. They are mainly vehicle specific and plug and play.

References

Vehicle parts {{auto-part-stub

See also

References