Bulbs that blow out quickly are usually the main symptom of most of the headlight issues that you’ll experience. If you replace your bulb and find out your headlight still doesn’t work, the headlight bulb socket might be defective. These steps explain how to replace a headlight socket yourself.

How to Diagnose and Fix a Bad Headlight Bulb Socket

Why Do Headlight Bulb Sockets Fail?

The bulb socket works in the same way in newer and older cars. It connects your headlight bulbs to the electrical system and ensures that they work. Sometimes the headlight socket wears out or corrodes from external weather elements, and this prevents voltage from getting to your headlight bulb.

Before deciding to fix or replace your headlight bulb socket, it’s important to first learn how to diagnose a faulty headlight bulb socket.

How to Diagnose a Bad Headlight Bulb Socket

Tools You’ll Need

Jumper cables
Test light

Steps for Diagnosing a Headlight Socket

Gain Access to the Headlight Socket
Gaining access to a headlight bulb socket is fairly easy on most cars. You can do so through the engine compartment or from underneath the vehicle. Both methods should allow you to get to the back of the headlight assembly.
Turn the Key to Accessory Mode
You’ll need to have the key turned into Accessory mode. This allows power to reach your car accessories such as the headlights without turning on the engine.

If you have a bad turn signal bulb socket that requires diagnosing, switch the turn signal on and leave it flashing before carrying out the diagnosis.
Connect the Test Light
The idea here is to test the problematic bulb socket for power and ground. With the hood open, hook your test light to the battery positive. You may need to use jumper cables to connect the test light to the battery if your test light is not long enough to reach the bulb socket.

Find an unpainted and clean metal surface under the vehicle’s hood to act as a good ground. Use it to check if the test light works. All you’ll need to do is touch the metal surface with the tip of the test light.
Test the Headlight Bulb Socket with the Test Light
Do the same thing for the bulb socket. Test the metal contacts with the test light to check for ground. You can try scratching some of the corrosion off. This should give you a steady light from the test light. However, corrosion and an unsteady light is an indication that your headlight socket is badly off and needs to be replaced.

How to Replace a Bad Headlight Socket

On some cars, replacing the headlight socket is a fairly easy process. All you need to do is pull out the socket from the connector and replace it with a new one.

Find Out the Light Bulb’s Type

When replacing your headlight socket, it’s important to first find out what type of light bulb your car uses. This will tell you what bulb socket you should get. Sockets are also rated by voltage depending on the power required for the bulb. Most exterior lights such as taillights, headlights, and fog lights have sockets rated between 12 and 14 volts.

Find Out the Socket’s Size and Material

Another important factor to consider is the size of the bulb socket. Sockets vary depending on the size of bulb they fit. It’s therefore, important to have the right specifications that match the bulb your car is using. You should also pay attention to the material used to make the socket. Ceramic is known to last longer than porcelain.

Pay attention to the type of socket that you need. This is normally based on the type of light bulb the car is using. The main types include:

Types of Light Sockets Needed for Certain Lights

Headlights

H7 and H4

Fog Lights

H11, H10, and H8

Side Direction Signals

T4W, T10, and W5W

Turn Signals

P21W for primary turn signals

Reverse Lights

7440, T20, and W21W

Shop Parts Mentioned in This Article

Headlight Assemblies

Fix a bad headlight socket yourself with quality auto parts at 1aauto.com

How to Replace a Headlight Socket