- Versatile Car Circuit Tester: Widely useful for continuity testing, voltage polarity testing, light checking, motor testing, and tracing and identifying short circuits and ground faults. It delivers accurate results. - Built-in flashlight: The tester has a built-in flashlight. To use the electrodes, place the red and black clips on the car battery's positive and negative terminals, making it easy to test and repair in the dark or to use as a lighting lamp. - Easy to use: Connect to the vehicle battery and drive positive and negative battery current to the tip by cranking the power switch forward or backward. - Polarity Output Test: Without pressing a button, use the probe on the front of the tester to detect an unknown polarity contact on the vehicle and check if it is charged. - Use scenarios: troubleshoot wiring harness shorts and ground faults; verify battery polarity after installation or replacement; inspect lighting and motor circuits, or perform testing in low-light conditions with the built-in flashlight.