1. Clean your H4 headlamps.
Your car's headlights are exposed to a variety of external elements, such as dirt, grime, dust, rocks and insects, which can build up and reduce the brightness of your H4 headlamps over time. Dirty headlights also limit your visibility on the road, putting you and other drivers at risk.
(1) Remove dirt, grime or dead insects with a damp microfiber cloth or sponge.
Do not use hot water or harsh chemicals that could damage the headlight's protective coating or lens.
(2) Gently wipe the H4 headlamp with headlamp cleaner or a warm water vinegar solution.
(3) Wipe them with a clean, soft towel or dry microfiber cloth.
2. Inspect the H4 headlamps.
Periodically evaluating the condition of your H4 headlamps can help you identify problems that may affect their performance or service life.
Check for cracks, scratches, discoloration or any signs of moisture on or inside the headlight cover. When seals or gaskets are damaged, moisture can enter the headlight assembly and cause premature bulb failure. If you notice any of these problems or experience abnormal lighting, consider replacing the headlight assembly or bulb.
3. Adjust the H4 headlamp target.
The targeting of your H4 headlamps can greatly affect your visibility and the safety of other drivers on the road. Headlights that are not aligned or aimed too high can blind other drivers and cause dangerous glare, while those that are pointed too low or off-center can reduce your visibility and cause accidents.
To adjust the target of your H4 headlamps, locate the adjustment screw near the headlight. You may need a Phillips screwdriver or a phillips wrench to turn them. Before adjusting, park your car on a flat surface about 25 feet from a wall or garage door. Turn on the headlights and mark the center of the beam with masking tape or chalk. Adjust the screws horizontally and vertically until the beam is aligned with the marks you made. Also, consider checking the H4 headlamp target after replacing the front or rear suspension, installing a lift kit, or carrying a heavy load that may change the ride height or angle.
4. Replace H4 headlamp bulbs.
Halogen H4 headlamp bulbs operate at high temperatures, which can cause filament burnout or bulb performance to deteriorate, especially if you use your headlights frequently or drive on bumpy roads that can cause vibration. Replacing your H4 headlamp bulb when it begins to show signs of dimming, discoloration or flickering will improve your visibility and ensure that your headlights function optimally.
To replace your H4 headlamp bulb, open the hood or access the headlight assembly from inside the vehicle, then remove the connector or cover that holds the bulb in place. Next, gently twist the old bulb in a counterclockwise direction to pull it out of its socket. Avoid touching the glass surface of the new bulb directly with your hand, as grease on your skin can create hot spots that can damage the filament or reduce output. Insert the new bulb into the socket and turn clockwise to install the new bulb. Finally, reconnect the connector or cover and test the headlight before driving.