Automotive relays are electromechanical switches utilizing an electromagnetic coil to remotely control a separate high-current circuit with a low-current signal. Commonly found in starting, lighting, fuel pump, and accessory systems, they allow high-amperage devices to be operated by the vehicle’s control modules and switches. Relays feature a coil resistance measured in ohms, alongside normally open (NO) and/or normally closed (NC) contact sets. Key specifications include coil voltage, contact current rating (amps), and physical footprint for correct application. Modern relays increasingly incorporate diode suppression for inductive load protection and may be solid-state for increased lifespan and faster switching.