Dome Light Cover



Replacing the lamp in an automotive dome light involves removing the dome light cover, replacing the lamp, and reinstalling the cover. But like any other small project, there are a few tricks of the trade that any experienced mechanic can tell you. Dome light covers are made of plastic that can become brittle over time. Many cars are more than a decade old, with some of more than 20 years old. In that amount of time the plastic undergoes degradation due to heat and other environmental effects. So, the first trick is to be gentle, as even covers that are not old and brittle can be broken with excessive force.



Remove the cover by first checking for screws that might be used to hold it. If there are any present, they are likely a Philips screw type and will require a Philips head screwdriver to remove them. If there are no visible screws, the cover will likely snap out for removal and snap back in to reinstall. Using a flathead screwdriver, slip the end underneath the plastic cover and gently pry the cover out, being careful not to apply so much force that you break the plastic. When the cover has been removed, lay it aside where it will not get broken, along with any screws.

The bulb should be clearly visible and generally looks like a glass tube with metal contacts at each end. The bulb can be removed easily by pushing either of the two metal contacts that touch the bulb at the ends away from the bulb. It should just fall out. Catch the bulb with a soft cotton towel, and be careful not to touch the bulb with your hands, as many bulbs these days are halogen bulbs. The halogen bulbs get very hot; so hot that finger prints from the oil on your skin can damage the glass.

When the bulb has been removed, inspect it. Like an ordinary house bulb, an inside filament that looks like it is broken means that bulb is bad. If the inside is covered with a silverish-grey opaque coating that prevents you from seeing the inside or seeing through it, it is probably bad, the coating being the result of metallic ions that were released inside when the element burned through, coating the interior glass. A third more complicated way that the bulb can be checked is with a digital ohm meter. Set the ohm meter to measure resistance, and connecting the leads of the meter to each end of the bulb. A bulb that is burned out will read infinite resistance on a meter. Newer bulbs might use LEDs, and none these techniques of checking will apply to LED bulb types. The easiest way to check any bulb is just to put a new bulb in and see if it works. Otherwise...