How to Fix the Accessory Power Outlet in a Car

by Justin Chacos
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Current technology has transformed a car’s accessory outlet from a mere cigarette lighter to a vital piece of the commuting puzzle. Paper maps have gone the way of cassette players with the advance of global positioning satellite navigation units and mapping applications on cellular phones. These 12-volt sources now power devices that provide navigation, traffic updates, weather conditions and emergency communication capabilities making car travel safer and more comfortable.

Determine If the Outlet Is Bad

Try a different accessory with the outlet. If the second accessory does power on, the problem is the original accessory and not the outlet. If both accessories fail to turn on in the outlet, the outlet is probably the culprit. If this is the case, proceed with further troubleshooting steps to determine the root cause of the outlet failure.

Check the Fuse

Accessory power outlets are protected by a fuse in a fuse block. It is there to prevent the outlet from overdrawing power and possibly creating a fire due to a short or misuse. Your owner's manual has a listing of all of the fuses in the car and a diagram highlighting the exact location of the fuse block. Remove the fuse using a fuse puller and inspect the metal line the plastic housing. If it is broken, replace it with a new fuse of the same amperage. The fuse block cover may have spare fuses you can use. Never use a replacement fuse with a higher amperage rating than the one you are replacing.

Check the Wiring

Use a multimeter’s DC volts setting to get an idea of what’s going on with the outlet. With the car ignition in the accessory position, insert the red lead into the outlet and make firm, direct contact with the conductor in the center of the outlet. Use the black lead to contact the side of the outlet without touching the red lead or the center conductor. If the meter reads anything below 12.0 volts or no current at all, find the problem in the wiring. Remove the negative battery cable and check for continuity between the side of the outlet and the outlet’s ground point, the outlet center conductor and any junction point between it and the fuse block, and hot shorts or short to ground. Repair any break in the wiring or shorts.

Replace the Outlet

If the fuse is OK and you didn’t find any breaks or shorts in the wiring, it is safe to suspect the outlet itself. A multimeter can help determine this as well. Unplug the power outlet from the wiring harness so that the outlet is electrically separated from the rest of the car. Jumper the red and black wire in the outlet's electrical connector, then insert the multimeter leads into the outlet as you did to check for voltage, but this time set the multimeter for continuity. Because the wires themselves have already been tested, an open circuit here will verify that the break is inside the outlet itself. If the meter reads no continuity, replace the outlet.

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