Testing a car relay with a multimeter is an essential skill for anyone interested in car maintenance or troubleshooting electrical issues. A faulty relay can lead to malfunctioning components in your vehicle, such as the starter, lights, or other critical systems. Fortunately, you don’t need to be an expert mechanic to diagnose a relay issue. By following a few simple steps and using a multimeter, you can quickly determine whether your relay is functioning correctly or needs to be replaced.
What is a Car Relay? A relay is an electrical switch that controls high-current circuits using low-current signals. In a car, relays are used to control devices like the fuel pump, starter motor, and other critical components. They have two primary functions： activating high-power circuits and ensuring that the car’s computer systems receive the necessary signals. Relays typically have five pins： two for the coil, one for a common terminal, one for normally open (NO) contacts, and one for normally closed (NC) contacts. Why Test a Car Relay? Over time, car relays can fail due to electrical issues, wear, or corrosion. A faulty relay can cause components like the starter or fuel pump to fail, which can lead to frustrating and expensive repairs. Testing the relay with a multimeter is a quick and effective way to diagnose whether the relay is functioning correctly or if it needs to be replaced.