All you need to know before replacing interior lights in your car

By Nick Marchenko, PhD

What are the interior car lights?

The name implies that in the contrast to exterior lights, these lamps illuminate the cabin itself. You might have heard two other names for this kind of lights - dome lights or courtesy lights. When people get in or out of the automobile, these bulbs automatically switch on and off. 

Interior lamps help the driver see better at night by providing improved vision for the controls. Today's vehicles have interior ambient lighting, which creates a unique atmosphere inside the car and makes it seem fancier. For more details on all kinds and types you can visit this interior light bulb guide on bulbsizechart.com, but here is a short list of them for general information.

Interior lights can be divided into categories by purpose and location:

- Map lights. Typically, there are two map lights in the front of the car - one on the ceiling and one above the rearview mirror. They illuminate maps, of course, documents for reading.

- Dome light. It's on the ceiling, usually in the center of the roof, hence the name, and illuminates the interior as you open the vehicle door.

- Trunk light. They are also called cargo area lights sometimes. This lamp is placed in the trunk and turns on when you open it, as the name implies.

- Glove compartment light. This bulb helps you find things in the glove compartment at night. 

- Floor lights (also called footwell lights) are pretty obvious.

- Vanity mirror lights. Interior car lights, on the other hand, are rather simple. These lamps are installed on or over the sun visor mirrors to shine your face brighter.

These are the main types of interior lights. As you can see, some of them are pretty straightforward, while others might be new to you. But all of them have one thing in common - they make your life inside the car more convenient and comfortable. So if one of your interior lamps burns out, don't hesitate to replace it as soon as possible.

How does a car interior light work?

When your automobile's interior lights are in good working order, they will generally come on when you open the door and shut off after you close it. This operation is dependent on a switch in the door jamb that opens when you open the car door and closes when you close it.

The interior lights are usually wired to the separate interior light circuit, which also powers other interior lights in your car, like the glove box light and map lights. This means that if one of these interior lights burns out, it could be an indicator that another interior light is about to go out as well.

Can you replace old interior light bulbs with LED?

LED bulbs are probably one of the most common types for cars. That is because they utilize semiconductor technology to emit light, which means they won't go out like bulbs. They last longer than incandescent bulbs and are less heat-generating. They also consume less electricity, resulting in fewer discharged batteries as a result of someone leaving the door open. You may go with bright white lights or multi-colored ones that change to add a touch of drama. LEDs can be used to replace interior lighting with no special tools or skills required.

Keep in mind, however, that not all LED bulbs are all-purpose. When choosing a replacement, make sure it is designed to work with your car's interior lighting system by consulting your car's manual or a linked chart from above. The wrong bulb could cause flickering or other problems like a short circuit. 

Are all interior car lights the same?

Unfortunately, as it is with the exterior bulbs, these lights are also very distinct. Not all of them are interchangeable, and you need to stay cautious. If your vehicle is an old-school model and has incandescent bulbs, you'll probably have to stick to that type. 

Some modern bulbs require special conditions like adaptors, wattage, and ballasts to function. Not to mention the socket size and shape they have to fit in. So, when changing an interior car light, always look up the requirements to find an appropriate replacement. 

How long do interior car lights stay on?

All types of lamps need power. And that resource is finite in your vehicle, so a responsible car owner like you is probably wondering how long can interior car lights stay on before they drain your battery completely. You have probably heard that LEDs are the most efficient bulbs on the market in terms of power consumption. By converting over 80% of energy into light and 20% to wasted heat, they utilize far less electricity from the automobile's electrical system. That said they still drain your battery at some rate, though it is not something to worry about.

It all depends on the battery, its state, and the type of bulbs (since some are more power-efficient than others), but a typical car battery has a capacity of 45 Ah and a vehicle electrical system voltage of 12 volts. So if you leave the interior lights on all night and two tiny bulbs with 10 watts burn, the battery will be exhausted after only 27 hours. That is enough time to come back in the morning and discover the issue before it's too late.

Is ambient lighting in cars illegal?

Since it is a relatively new concept, many carmakers are still in the process of making ambient lighting systems that will not violate the law. In some cases, they are successful, and in others, they are not. The thing you need to keep in mind that safety is the top priority.

It is advised to turn off ambient lights while driving. You are free to use them as you wish when the car is safely parked.

While there are no specific laws against it, some states have started to crack down on distracted driving. So if passengers are using your car's ambient lighting system to read a book or put on makeup, you could be pulled over. The best practice is to use common sense and only use the lights when you're not driving. 

Nick Marchenko, PhD

Industrial Engineer & Automotive Content Specialist

Nick writes in-depth guides on car clubs, engine specs, vehicle ownership, and modifications, combining engineering knowledge with automotive passion.

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