The Power Probe 4 is a multi-use Circuit Tester with built-in diagnostic power. This tool simplifies the testing of fuse boxes, verifies correct operation of motors, lights, relays, sensors, wires, communications circuits and computer drivers. The large LCD color display makes viewing live test information and mode selection simplified in even direct sunlight or complete darkness. The Power Probe IV is the next generation of Power Probe Circuit Testers. Now loaded with powerful multi-meter functions, advanced diagnostic test modes, an easy to read color LCD display and a new rugged water and dust resistant housing, the Power Probe IV is designed to give you years of trouble free testing, even in the most demanding work environments. The Power Probe IV is connected to the battery, you can apply battery power or battery ground directly to the tip of the tool. You can energize and activate components to verify their correct operation. This is real dynamic component testing and the only true way to test an active component.