Circuit Tester, 6-24V Test Light with 135 Inch PU Extended Spring Wire,Steel Probe Vehicle Circuits Low DC Voltage Light Tester, Automotive Test Light electronic control system Designed for detecting low voltage circuit faults in transportation machinery. Used to detect power, ground and find shorts and breaks in wires. Quickly check automotive headlights, taillights, turn signal circuits, faulty sockets, connections, fuses, socket tester.broken wires and more.Used to detect power, ground and find shorts and breaks in wires，This upgrade circuit test light is a bidirectional voltage tester. You can attach the alligator clamp either to negative or positive ground, there is also a light emitting diode on the circuit board for polarity indication, red light indicates positive polarity and green light indicates negative polarity. circuit test is ideal for checking various vehicles electrical circuits, also for testing other 6V / 12V /24V DC DC wirings and circuits.