First of all, the workings of automotive turn signals involve two main parts: the circuit and the bulb. When the driver turns on the turn signal switch, electric current passes through the vehicle's electrical system and into the corresponding turn signal bulb. At this point, the resistance inside the bulb heats up, causing the filament to glow. This is the basic principle behind how turn signals come on. Secondly, the working principle of turn signals also includes the transmission of control signals. In the vehicle's turn signal system, the turn signal switch plays a very important role. When the driver turns on the turn signal switch, the switch sends a signal to the vehicle's control unit telling it which turn signal bulb to light up, thus realizing the turn signal lighting.