How does a car turn signal work?

The working principle of car turn signals is to control the current flow through a flasher, causing the lights to flash at a specific frequency to indicate turning intention. When the driver activates the turn signal switch to the left or right position, current flows from the flasher relay through the switch to the corresponding side bulb and grounds to complete the circuit, at which point the flasher begins operation. Traditional thermal flashers utilize the thermal expansion and contraction of bimetallic strips to periodically complete the circuit; capacitor-type flashers operate through capacitor charge/discharge cycles to trigger relay action; while modern electronic flashers employ transistor switching characteristics combined with capacitor charge/discharge, enabling more stable control of flash frequency. Turn signals typically use xenon tubes or LED light sources, with left-right alternating flashing controlled by a microcontroller, and their amber colour complies with regulatory requirements. For proper use, they should be activated approximately 30-100 meters before turning and at least 3 seconds prior to lane changes to ensure adequate reaction time for surrounding vehicles. The turn signal system, together with position lamps, license plate lamps, and other lighting elements, constitutes the vehicle's lighting safety system and serves as a critical component for communicating driving intentions during operation.