Testing a communication relay with a multimeter is an essential task for anyone working with electronic circuits or systems that rely on relays for switching. A relay is an electrically operated switch used in various applications, including communication systems, to control larger currents with smaller control signals. Whether you’re diagnosing a malfunctioning relay or ensuring the functionality of a new one, the multimeter can be your best tool for the job.

This guide will walk you through the process of testing a communication relay using a multimeter, covering the essential steps involved in checking both the coil and the contacts of the relay. Let’s get started. What You Need Before beginning the testing procedure, ensure that you have the following tools and equipment： Multimeter： A digital multimeter is ideal for most tests, but an analog one can also suffice. Relay： The relay you intend to test, preferably unpowered. Power Source： For activating the relay coil if necessary (this will depend on the relay type). Safety Equipment： Always take necessary precautions when working with electrical components.