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How to Diagnose and Repair a Broken Auto Light Socket

Headlight out?
Use these four simple steps to determine if your bad headlight or taillight is caused by a burnt-out bulb, a corroded socket or a bad wire.

By the DIY experts of The Family Handyman Magazine

Step 1: Replace the bulb

When a headlight goes out, the problem is usually a bad bulb, which is easily replaced. However, the problem could also be a corroded socket or a bad wire. Keep in mind that when several lights are out, such as both headlamps or both taillights, the problem is most likely a fuse. If the fuse is bad, you can replace it and most likely be on your way.

In this article, we'll show you how to replace the bulb, and if that fails, we'll show you how to diagnose a bad socket and probe the wiring with a simple 12-volt automotive test light.

Step 2: Clean the socket

Step 3: Test the socket

Step 4: Test for power at the wires

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Required Tools for this Project

Have the necessary tools for this DIY project lined up before you start—you’ll save time and frustration.

The only tools you'll need are a 12-volt auto test light, a small screwdriver or wire brush for scraping corrosion, and (possibly) a “torxrdquo tip screwdriver.

Required Materials for this Project

Avoid last-minute shopping trips by having all your materials ready ahead of time. Here's a list.

    • Headlamp bulb
    • Electrical contact cleaner

Comments from DIY Community Members

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August 16, 9:54 AM [GMT -5]

If I have a single bulb for both high and low beams, how would I show power at both live terminals at the socket without moving the dimmer switch?

September 28, 12:56 AM [GMT -5]

After frying one socket, then replacing it, only to have a new bulb melt like a chocolate bar down into the socket, I found a technical bulletin on my daughters car advising owners to clean off the ground wires to the headlight assembly. I located both wires attached to the radiator support. I used a wire brush and some sandpaper to clean the connections, the radiator support, screws and even rolled up a small piece of sandpaper to clean out the screw holes. No more problems.

May 23, 12:38 PM [GMT -5]

In step three it says if two of the three contacts light up but the bulb doesnt light up, replace the socket. But if two of the three contacts are ok, why would you replace the socket? Im confused

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How to Diagnose and Repair a Broken Auto Light Socket

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