What controls the turn signal?

The control core of the turn signal is the flasher relay, which generates pulse signals through internal circuit switching to achieve light flashing. Depending on the relay type, the working principles can be divided into three categories: thermal-type relays utilize current's thermal effect to expand a bimetallic strip and break contact (e.g., hot-wire type) or cause sudden spring plate movement (e.g., blade type); capacitor-type relies on charge/discharge timing characteristics to control contact switching; while electronic-type precisely regulates flash frequency through transistor components. Modern vehicles predominantly employ electronic relays, with some models integrating Body Control Modules (BCM) for intelligent management. The turn signal system typically comprises front, rear, and side lamp assemblies, operating at 20-30 watts with a flash rate of 60-120 cycles per minute. Systems use either xenon tubes or LED light sources, with the latter becoming mainstream due to extended lifespan and rapid response (illumination within 1.5 seconds). For troubleshooting, priority inspection should focus on the relay, fuse, and wiring connections to ensure proper turn signal operation for effective roadway communication.