It is so easy to take for granted that your car interior will be well-lit when you open the door or that your dashboard lights will make driving a little bit easier. What do you do, though, when you are left in the dark?
Before you panic or invest time and money with a mechanic, there are a few things you can easily do yourself to help determine what the problem is -- or whether there really is a problem. Depending on your skill and confidence level, you might decide to utilize a professional mechanic as some of these checks get more in-depth.
*Check the Switches
Let's start with the dome light, that thing that is supposed to light up your car interior each time you open a door. The simplest thing to do is to make sure that the switch on the dome light is actually set to automatic; it's easier than you think to knock into the toggle switch. If you are not sure where the toggle switch is (this three-position switch is usually found on the side of the dome light), check your owners manual for detailed info. If the switch setting is correct but the light doesn't go on when a certain door is opened, then check the other doors to see whether the light goes on. If the light works with any of the other doors, then there may be a stuck door latch or button on the original door you were using; spray the button with WD-40, and then open and close it a few times to work the lubricant in.
*Check the Fuses
If the light is still not working, check your fuses. Most cars have two fuse boxes, one inside the car on the driver's side of the dash and one under the hood. The fuse box inside the car is for low-voltage items, such as the dome light, dashboard lights, most headlights, taillights, the glove compartment light, the trunk light and the cigarette lighter. Once again, your owners manual can help you find the exact location in your car. A schematic on the fuse box cover will tell you which fuse belongs to which item. Though you probably can easily see which fuse is blown, sometimes using a voltmeter to check will help. If you need to replace a fuse, make sure you are replacing it with one that is the right size and amperage; bring the original fuse into the auto parts store to match it up (assuming it was the original/correct one already).
*Check the Bulb
Checking bulbs is usually more complicated than checking the fuse box, which is why it's listed after that step. Dome light bulbs are relatively easy to check. Just use a flat-head screwdriver to pop the cover off. Be careful not to break any tabs. Once again, make sure you are replacing any burned-out bulb with one that is the correct size and voltage/wattage. Check to make sure the bulb works before popping the cover back on.
Dashboard bulbs are not so easy to get to. Replacing one often means pulling the bottom of the dashboard out in order to snake your hand behind it and locate any burned-out bulbs. Finding and pulling out the burned-out bulb and then replacing it is usually done blindly, as the wiring and sockets are built into the back of the dash panel.
*Check for Electrical Shorts
Unless you have electrical experience, this job may be better left in a professional's hands. There are two types of shorts. There's a simple short, when the wiring is damaged. With this type of short, turning the car on can blow a fuse. And there is a dead short, when the electrical wiring, although damaged, does let current run through but can cause your car's battery to drain.
The wires for the dome light are normally found under the headliner. You will have to remove the visors and pull the fabric away from the roof to view the wires. Using a voltmeter is a good idea to check the connections. Electrical tape may be sufficient to mend frayed wiring. Like the bulbs, dashboard wiring is difficult to get to and assess for damage. Missing a frayed wire or a dead short could kill your battery or even start an electrical fire, so if you do not know what you are doing, it is probably worth going to a mechanic at this level.