A turn signal is a lever or switch operated component in a vehicle that uses a blinking light to indicate when a driver is attempting to change directions. Turn signals are typically fitted with a thermal flasher and automatically turns itself off once the driver has completed his turn.
A turn signal is powered by the vehicle's battery and is automatically active when the ignition key is turned on. When the turn signal lever or switch is activated, the power being sent to the turn signal is sent to either the right or left turn signal light. When the switch is not activated, the power current is stopped at the turn signal electrical switch.