An automotive relay is an electrical switch that uses a low-voltage signal to control a higher-voltage current. In the case of headlights, the automotive relay is responsible for switching the high-power circuit of the headlights on and off without overloading the vehicle’s primary switch. The relay consists of an electromagnet, a movable contact, and a fixed contact. When a small current flows through the coil, it generates a magnetic field that pulls the movable contact toward the fixed contact, allowing a larger current to flow through the headlight circuit.