The increased use of electronics in today's automobiles has complicated the control of circuits and actuators. Manufacturers use relays to control a variety of complex circuits--for example, those involving actuators and other components like the A/C clutch, electronic cooling fans, and blower motors. Relays allow a switch or processor to control a circuit that requires a higher amperage flow. In essence, a relay is nothing more than a small electromagnet that allows the processor or remote switch to connect or disconnect electrical current to a component. Over the past few years, the authors have served as judges in regional SkillsUSA competitions in Missouri and Kansas and at the national SkillsUSA championships. In the course of those activities, they have noticed that many students have problems with stations that involve the operation of relays. Most students seem to have a limited understanding of how a relay works, as well as how to diagnose and troubleshoot this electrical device. This article provides information on the operation and testing of automotive relays, along with related activities that teachers can use with their students. (Contains 7 figures and 4 photos.)