How to use an automotive test light to check power and ground

There are two types of automotive test lights; powered and unpowered. The unpowered versions are the most common and least costly. I’ll show you how to use an unpowered test light to check fuses, connectors and ground connections.

How to test your test light ground connection

Before using a test light, you should test it using your car battery. That confirms the bulb is working and you’ve got a good ground connection.

How to test a fuse using a test light

Some auto fuses have power even with the key out of the ignition switch, but most don’t. Unless you know whether the fuse is “Hot at all times”, you should turn the key to the RUN position so each fuse is powered.

Then connect use your test light to check the fuses.

Test a ground connection with a test light

©, 2023 Rick Muscoplat

Posted on April 3, 2023 by Rick Muscoplat