Unlike your household bulbs, automotive bulbs do not unscrew - you generally either pull them straight out of the bulb-holder, unclip them, or gently push them in, rotate them 1/4-turn counterclockwise and pull them out.
Bulbs with a cylindrical base are called "bayonet" bulbs and are used primarily on older vehicles. On this type of bulb, the socket is spring-loaded, and posts on the side of the bulb are what actually hold the bulb in place. When there are dual filaments, the posts are staggered so the bulb can only be installed one way. When installing a staggered-post bulb, if you can't easily push it in and rotate it 1/4-turn clockwise, you probably need to pull it out, rotate it 1/4-turn, and try again.
While the bulb is out, inspect the socket for damage and corrosion. On exterior bulbs, corrosion is a very common cause of lighting problems that can be easily cleaned with a wire brush.
You can see that removing the bulbs is easy. What's often a little more difficult is figuring out how to access the bulbs. This is where your Haynes manual will be a big help. But we'll give you some general guidelines here so you'll know what to expect.
There are three common ways to get to the brake, turn signal, taillight and back-up light bulbs: You'll either access them from inside the trunk or cargo compartment, remove the lens for access, or remove the entire taillight assembly. All of these access methods are actually very easy.
If you're not sure how the bulbs come out, first look at the lens. If you see screws, remove them and pull the lens off. Now the bulbs are easily accessed for removal. When replacing the lens, be sure the gasket is in place to keep water out.
If you don't see any screws on the lens, open the trunk or access panel and look at the areas behind and around the taillight assembly. If you see fasteners here, remove them. This will either allow access to the rear of the taillight assembly or release the taillight assembly completely. You can then rotate the exposed bulb holders 1/4-turn counterclockwise and pull them out of the taillight assembly.
Most vehicles today use halogen bulbs for the headlights. To replace a halogen bulb, open the hood and remove any covers or components necessary to access the rear of the headlight housing. In some cases, you'll have to remove the headlight housing itself. Disconnect the electrical connector, then rotate the bulb holder or lock ring counterclockwise and pull the bulb holder out of the housing. Reverse the procedure to replace the bulb. Be sure not to touch the bulb glass, since your finger oils can cause the bulb to overheat and fail prematurely. If you do touch the glass, clean it with rubbing alcohol.
On most vehicles, the front turn signal and side-marker lights are combined into the headlight housing and are accessed from the same area as the headlight bulbs.
For access to many interior bulbs, all you need to do is unclip the lens. Sometimes a small screwdriver can help to pry off the lens. The plastic lenses can easily be broken, so pry gently. To replace instrument cluster bulbs, you'll often have to remove the cluster assembly - the bulb holders attach to the rear of the cluster.
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