How to Replace or Adjust a Headlight Bulb in 2021

f you’re driving down the street at night and all of a sudden your scope of vision isn’t illuminated, is it the street lights or your headlights? If you determine it’s a headlight on your car, don’t worry. Replacing or adjusting a headlight bulb isn’t very difficult and is easily a do-it-yourself project, if you are so inclined. Reliable Imports is experienced in working on headlights and headlight bulbs, as well as repairing electrical issues. In this article, we want to give you the information you need in order to diagnose the problem, and replace or adjust a headlight bulb. But, as always, we are here to help in any way we can.


Diagnosing the Problem - Replace, Adjust, or Something Else?

First, you need to determine if the headlight bulb is out, has slipped out of alignment, or the problem is something more serious. Look at the headlights to see if it is just one bulb. If only one bulb is out, try tapping on the light with your fist. Sometimes this will make the bulb go back on. This means a filament is burned out because when you hit it, the filament shakes and makes contact. This may hold for a while until you can replace the bulb. 


Your problem may be beyond just replacing the bulb. But, you won’t know this until you do change the bulb. So, after replacing the headlight bulb, if it is still not working, you may need to take the car to a professional repair shop for them to properly diagnose the problem and fix it.


However, if the bulb is lit, it may have slipped out of place. It may be difficult to actually see on a street, so you may need to move the car for a proper diagnosis. See the steps below for Adjusting the Headlight Bulb. 

Causes of Car Headlights Going Out

There are several reasons why a car headlight goes out, including:

The Bulb is Old

The most common cause for a burned-out light is age. When this is the case, one bulb will go out, then another one not long after. Because, guess what? Both bulbs are old!


Extreme Temperatures

Extreme heat and cold can impact the filament and can cause headlights to burn out. 



A cause of dimming lights can be oxidation of the plastic housing, causing it to appear white or yellow. This coloration diminishes the beam of light and necessitates replacing the entire headlight assembly.


Cracks in Bulb Housing

Any cracks in the housing can cause halogen bulbs to burn out due to moisture. You can replace the bulb and within a day or two it can blow because of the humidity and wetness.


Steps for Replacing a Headlight Bulb

Step 1: Get the Owner’s Manual

Refer to the owner’s manual for details about changing a headlight for your specific vehicle and what bulb you need to purchase.

Step 2: Turn the Car Off

For safety, turn the car off and take the keys out of the ignition.

Step 3: Access the Bulb 

Gain access to the headlight’s bulb by opening the hood and removing the lamp connections (the bulb power wires) at the back of the headlight housing. There are usually three wires attached to the base of the light bulb that you can disconnect by pushing down on the clip or cap that holds them in place. Some vehicles provide added space for service through small hinged or rotating panels inside the front wheel wells.


Some vehicles require removal of various splash shields, air-cleaner housings, and even washer-fluid bottles for full access to the headlight. It’s good to keep a pair of mechanic’s or latex gloves, a flashlight, a flat-bladed screwdriver, a small box of sockets, and a pair of needle-nose pliers handy. (This advice may be for a true do-it-yourselfer.)

Step 4: Extract the Old Headlight

After the wires are disconnected, remove the back of the headlight holder and remove the old bulb by holding onto the base. You may need to rotate the bulb a bit to get it free to pull out.


Step 5: Install the New Bulb


It’s important to handle the new bulb with tissues or gloves because oils from your skin and contamination from dirt, even the smallest amount, will cause early failure. Your bulb may come from the auto parts store with dielectric grease for a weather-resistant connection on all the lamp plugs and terminals. If it doesn’t come with the bulb, get some. It doesn’t take much, but it’s important. Note that the bulb retaining screws are smaller than the headlamp-adjustment screws.


The Replacement Headlight Bulb Doesn’t Work


If you replace the bulb and it still isn’t working, then you need to test the fuses and the wiring. If the car has power going to the fuses and there is no power going to the light, the problem is in the wiring. Perhaps a wire broke or got pinched.


Another consideration is that the replacement bulb is halogen and isn’t appropriate for your plug. Halogen bulbs run very hot. Some auto parts stores sell brighter or colored replacements that are marketed as being better for visibility but run even hotter. A stock OEM plug that is in the car from the factory can’t withstand the extra wattage. So, it will begin to melt and make a bad connection, causing the light to go out. If this happens, you will need to change the entire light socket. At this point, you may want to seek professional help.


Steps for Adjusting the Headlight Bulb

Step 1: Determining the Adjustment 

Park the car on flat ground and make sure the car is level. To level the car, you will need to unload heavy cargo, fill the gas tank to full, and make sure tire pressure is correct on all four tires. Then, pull the car as close to a plain wall as possible and turn on the lights. Now, you can find the centers of the low-beam headlights. Mark both spots with a single piece of horizontal tape in the middle. Then, put a piece of tape about 2 feet long running vertically through the center of the low beams. Now you should be able to determine if the bulb needs to be adjusted.

Step 2: Locate the Adjusters

After determining that the headlight bulb needs to be adjusted, find the adjusters. Generally, the adjusters are a screw or bolt on the back or side of the headlight unit. These may not be marked, but are gray or silver and stand out from the black headlight housing. Some vertical adjusters are located on the bottom of the unit, which makes access more difficult. Check the owner’s manual for information on the location of the adjusters. Sometimes automakers cut a hole in the vehicle’s metal structure that allows access to them.

Step 3: Line It Up

After you find the adjusters, back up the vehicle until it’s 25 feet from the wall. Measure this distance to be sure it is accurate. Some specific manufacturers recommend different distances, for example, Chrysler is 33 feet while Toyota is 10 feet. Again, check the owner’s manual for your particular vehicle.


Block one headlight and look at where the other beam shines compared to the markings you made on the wall. For vertical aim, the top of the most intense part of the beam should be at or below the centerline of the horizontal tapeline. For horizontal aim, the most intense part of the beam should be to the right of the vertical tapeline. This aim is important so that you don’t blind oncoming traffic and so you can see the side of the road and anything that may suddenly appear coming into your path.


Make adjustments if the aim is askew by turning the adjusters a quarter of a turn at a time and see where the new alignment falls.  Repeat the same procedure for the other headlight.


Contact Reliable Imports for Replacing or Adjusting Headlight Bulbs

If a headlight goes out on your vehicle or you think the headlights need to be adjusted, contact us. We can diagnose the problem easily and make the necessary adjustments and fixes so you don’t have to. If you have repairs and service needs, schedule an appointment by calling (919) 324-3019 or complete our contact form.


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