How to Use a Test Light to Check a Circuit?

[ZaneAnn]

Test Light Check Circuit Method: Connect one end of the test light to the negative terminal of the battery or ground, and the other end to the point being tested. If the test light illuminates, it indicates that the circuit is live; otherwise, the circuit is dead. Below is relevant information about automotive test lights: 1. Definition: Automotive test lights are generally divided into two types: diode test lights and ordinary bulb test lights. Test lights are simple, convenient, and intuitive to use, making them widely applied in automotive testing. However, it's important to note that when testing circuits connected to automotive electronic control units, ordinary bulb test lights should not be used. Only test lights made with light-emitting diodes (LEDs) should be used to avoid damaging automotive electronic components. 2. Principle: Some test lights may have a wire or steel needle attached, with the tip sharpened to pierce wire harnesses or cables. During use, one wire connects to the positive terminal and the other to the negative terminal. As long as one end is connected to the positive and the other to the negative, the bulb will light up.