Auto Repair For Dummies, 2nd Edition
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Before attempting to replace or adjust your headlights, you need to know whether you have halogen or xenon headlamps or the old-style sealed-beam units. You can tell which type of headlights you have by looking at them when they’re on at night.

Headlights with sealed-beam units are quickly going out of style. The light they give off is just plain white. Many modern vehicles have halogen headlights. The newest models often come with HID (high intensity discharge lamps), also called xenon or bi-xenon lamps. Light from xenon lamps has a bluish cast.

Although they are far more powerful than sealed-beam units and enable a driver to see 20 percent farther, halogen and xenon units require less power to operate. Xenon are the brightest, have the longest life, and consume the least power. Halogen and xenon headlamps have also allowed designers to get pretty creative with shapes because they use small, replaceable lamps that don’t have to be contained in round or rectangular housings.

To replace a bulb on a halogen or xenon headlamp, turn off the car and follow these steps:

Open the hood and find the wiring leading to the electrical connector that plugs into the bulb assembly.

Open the hood and find the wiring leading to the electrical connector that plugs into the bulb assembly.

Use this figure to help you find the connector.

Remove the connector.

The connector can be held in place by a ring that unlocks by twisting it counterclockwise, by a little catch that you need to press down while pulling on the plug, or by a metal clip that pulls off (don’t lose it!).

Pull out the bulb assembly, remove the old bulb, and install the replacement.

Don’t touch the replacement glass bulb! Natural oils from the skin on your fingers create a hotspot that can cause the new bulb to burn out prematurely. Instead, handle the bulb by its plastic base or the metallic tip, if it has one. Also, these fragile bulbs are filled with gas under pressure, so be careful to avoid breaking them.

Replace everything, replug the connector, and turn on your headlamps.

If the bulb is still out and the fuse is okay, have a professional diagnose and fix the problem.

Adjust the beam, if necessary.

Adjust the beam, if necessary.

Because HID headlamps are so intensely bright, it’s most important that they be properly focused to avoid temporarily blinding other drivers, pedestrians, or animals.

If you need to adjust the alignment of a halogen headlamp, it has two adjusting screws, as shown here. The screw on the bottom angles the beam higher or lower; the one at the top or side focuses the beam to the left or right. The beams should illuminate the stretch of road ahead of you, not the oncoming traffic. If your lights are really out of whack, have a service station adjust them for you.

About This Article

This article is from the book:

About the book author:

Deanna Sclar is an acclaimed auto repair expert. She has appeared on hundreds of radio and TV shows, including NBC's Today show and the NBCNightly News. Sclar lectures internationally on the ecological impact of vehicles and is active in promoting residential solar energy programs. Sclar is also the author of Buying a Car For Dummies.

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