Mechanics

Test Light Instructions

A test light is used to check the continuity of an electrical circuit. A test light utilizes a bulb held in a probe attached to a sharply pointed rod with a grounding lead. This design is optimal for piercing a wire, testing a fuse or checking the surface charge of a battery. A test light is easy to use, first connect the ground clip to a known good ground source, the battery negative terminal is best but any grounded metal source will work. 

Then connect the pointed end of the test light to desired circuit to be tested. If power is present the bulb will illuminate informing you the circuit has power and is operating properly. Also you can reverse the test light lead to the positive battery to be able to check for system ground continuity. (Note: A test light should be used for basic electrical circuits only. Do not use a test light to check computer related circuits, a voltmeter should be used in these cases.)

Automotive Test Light -  Circuit Tester
Automotive Test Light -  Circuit Tester

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Written by
Co-Founder and CEO of 2CarPros.com
35 years in the automotive repair field, ASE Master Technician, Advanced Electrical and Mechanical Theory.


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Article first published (Updated 2013-08-16)