A relay in a car is an electromagnetic switch used to control high-power electrical devices using a low-power signal. It consists of a coil that, when energized, creates a magnetic field which closes or opens a set of contacts. This action controls the flow of current to a particular circuit or component. A well-functioning relay ensures smooth operation of critical systems, but like all components, relays are susceptible to failure over time.

    Common Relay Failure Modes

    Contact Wear and Corrosion

     Over time, the contacts inside a relay can wear out or corrode due to repeated use and exposure to high current loads. Corrosion often results from the constant heating and cooling cycles, especially in automotive environments where moisture and dirt can accelerate degradation. When the contacts become worn or corroded, the relay may fail to establish a proper electrical connection, leading to erratic operation or complete failure of the connected system. For example, a worn-out starter relay might cause intermittent engine cranking issues or prevent the engine from starting altogether.