- Car Truck Circuit Test Pen: 12V test light, 12V wire tester probe, test light with clamp. Professional car electric tester and circuit test light for testing circuits from 6V/12V/24V. Light in the handle illuminates when the circuit connection is complete; test light is lightweight and easy to carry. - Electric Current Tester with Indicator Light: Digital LED automotive test light and auto voltage continuity test. Effective for testing automotive DC and AC voltage and suitable for home electric or garage equipment testing. When the test pen tip glows red and the pen beeps, there is voltage present; light in the handle glows when the circuit connection is complete. - How to Use: Electrical circuit tester. Connect the alligator clip to ground and connect the probe to the test circuit. When the circuit is connected, the handle lights up. If the indicator of the auto car truck wire piercing cord voltage circuit tester is not lit, there is no power. - Long Probe With Alligator Clip: Long probe with alligator clip to reach tight places. Suitable for passenger cars, sedans, SUVs, RVs, and trucks. A professional tool for detecting open circuits, fuses, tuning signal lights, headlights, taillights, and more.