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Retire Your Old Automotive Test Light

Invest in a computer-safe test light and retire the old incandescent test light. The old one can damage sensitive electronics in your car.

By the DIY experts of The Family Handyman Magazine

Buy a computer-safe test light for auto trouble-shooting

Using a test light to check for circuit voltage is a tried-and-true diagnostic method. But if you probe a computerized circuit with your old incandescent test light, you can fry some sensitive and expensive electronics. Since almost every circuit in a late-model car is controlled by a computer, it's best to say goodbye to your old test light and invest in a computer-safe test light. These don't pull any power from the tested circuit. Instead, they plug into the cigarette lighter. A red LED means the circuit has power. A green LED means the circuit is connected to ground.

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December 15, 2:05 PM [GMT -5]

Many of my projects require being away from the inside of the vehicle. In some cases, I would need 20 feet of cord, especially if I am installing electrical components on the rear of the truck. Many of the test lights like the one you showed only have a six foot coiled cable.

October 27, 5:02 AM [GMT -5]

Does anyone know the brand name of the LED test light shown in the article?

April 22, 6:09 AM [GMT -5]

Some of my auto parts getting older it is time to change it,Thank for your information.

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