The starter motor relay is an electromagnetic switch that is responsible for engaging the starter motor when the ignition key is turned. It allows a low-current signal from the ignition switch to control a high-current circuit from the battery to the starter motor. This design minimizes the amount of current that flows through the ignition switch, protecting it from wear and potential damage.

    How Does It Work?

    When the driver turns the ignition key to the “start” position, a small amount of current flows through the ignition switch to the starter relay’s coil. This triggers the electromagnetic mechanism within the relay. As the coil energizes, it creates a magnetic field that pulls a metal armature, closing the relay contacts. This connection allows a much larger current to flow directly from the battery to the starter motor, initiating the engine's cranking process. Once the engine starts and the ignition key is released, the relay coil is de-energized, opening the contacts and cutting off the power to the starter motor.