Behind the Wheel, Car Culture

Headlights FAQ: “What’s Wrong with My Car’s Lights?”

February 28, 2019
Having problems with your car’s headlights? Millions of car owners around the world are right there with you, shoddy headlamps and all. But if you’ve got questions related to your vehicle headlights, I’ve got answers—and solutions—that should put those problems in your rearview.

Why are my headlights so dim?

You’re in some automotive Twilight Zone episode, sitting between “headlights quit working” and “headlights are too bright” dimensions. Fortunately, getting out of this paranormal predicament is fairly simple. Although bad headlight switches and alternators can cause issues with hazy headlamps, dim headlights are usually caused by either old-bulb filaments or corroded ground wires.

  • To diagnose your headlight ailment, open your headlamp assembly and inspect the bulb. Notice any gray, brown, or black residue inside? If so, purchase new lights from your dealer or at a headlight store, and replace those suckers.
  • If your headlight bulbs look clear, check under the hood. Follow your headlight’s wires back to where they connect to the vehicle. With a wrench, unscrew the ground cable from its point of connection. Use a wire brush to scrub away any corrosion or dirt. Reconnect the cables and inspect your light’s brightness.
  • If neither solution solves your problem, consider taking a trip to your auto service center. They’ll help.

Why are headlights so bright?

If you feel like car headlights are getting brighter each year, you’re not crazy. With LED, halogen, HID, and xenon technology becoming a new norm, high-intensity headlights on the road today can cause temporary blindness, or “road dazzle,” putting other drivers at risk. Avoiding bright lights can be difficult – look toward the side of the road when needed – if not altogether impossible. In fact, 88% of drivers surveyed believe that modern headlights are too bright.

LED vs. HID vs. Halogen vs. Xenon: What are the differences?

Halogen: Until recently, halogen headlamps have long been the most common type of car headlight. They’re easier to manufacture and install, which ultimately means they’re cheap. Most halogen bulbs sit in the color temperature range between 3,000 and 4,500 KELVIN (K) and emit a warm or cool white light. Because halogen light bulbs use filaments, they have a shorter lifespan than alternative bulbs—usually 400 hours.

LED: Newer LED car headlights are more popular now than they were 20 years ago, when LED bulbs were costly and inefficient. Today, LED headlamps are much cheaper and can operate for up to 5,000 hours. They produce up to 6,000K and emit a crisp, daylight-mimicking glow. Cars with DRL, or Daytime Running Lights, usually utilize LEDs.

Xenon: Oftentimes optional on range-topping models, xenon headlights last up to 3,000 hours and produce a more natural light with a color temperature ranging from 4,000K to 6,000K. Unlike LEDs, xenon headlamps are slightly less efficient, as they require up to 30,000 volts to ignite the xenon gas inside.

HID: High-Intensity Discharge (HID) headlights – which are offshoots of xenon lights – are typically installed as aftermarket parts or via a headlight conversion kit. Most people install HID bulbs because of their vast color options; HID color temperatures range from 3000K to nearly 30,000K (purple). If you see a car with blue headlights, they’re rolling with HID.

Are HID headlights illegal?

Genuine OEM HID car lights are legal; aftermarket HID conversion kits are only road legal if marked with an “E” or “ECE R99” grade. So, you can change your headlights to appear blue or change colors. However, the original headlamp unit must also be replaced entirely with a new US-manufactured HID conversion unit to be legal. Generally speaking, any headlight over 6,000K could present problems with the fuzz. You may not be breaking the law, but there are safety concerns associated with bright or colored HID lights.

Why are my headlights flickering on and off?

The most common reasons for flickering car headlights: an old battery, failing bulbs, or a faulty electrical system or component.

  • First, test your car battery and replace it if it’s old. If the battery is solid, clean the terminals.
  • Replace any old halogen bulbs—they usually only last for 400 hours, as mentioned above.
  • If you also have problems with your car starting, you may have a bad alternator rectifier, which is responsible for converting voltage from AC to DC. This failure can cause a ripple effect that makes headlights flicker or fade, especially when the car is parked.
  • Check in with your mechanic or car maintenance shop for additional insight and assistance.

Should I be concerned about my headlights steaming up with condensation?

Don’t fret; moisture inside your headlight is completely natural. When the bulbs warm up – halogen and xenon lights generate heat – and the outer plastic headlamp cover cools, condensation can form inside. Driving your vehicle for a moment will normally de-fog fogged headlights. However, pooling water inside your headlight assembly can be caused by cracks, poor headlamp seals, and blocked vents. Inspect your headlight units for any signs of damage.

How do I adjust or realign my headlights?

If your car lights aren’t angled well, your reaction time is drastically diminished. Correcting your headlight angle is the best solution—even if it’s quite a tedious task.
  • To begin, you’ll need to find the headlight adjustment area, which is usually located somewhere within or beneath the headlight housing. The adjusters are typically in the form of bolts or screws. (Check your owner’s manual or speak with an auto dealer near you for advice.)
  • At night or in the dark, face your vehicle toward a blank wall, like inside your garage, with about 30 feet of space between the wall and your headlights.
  • Block one headlamp with an object, like a piece of cardboard. With a pencil or tape, mark the wall where the other light is most intense. Repeat with the other headlight.
  • Make your adjustments, using your manual’s suggested specifications and guidelines.

What is dynamic bending light?

Many new car models include headlights that move with the car. These types of headlights feature Dynamic Bending Light technology, which gives drivers a wider point of view going around turns.

What are the differences between headlights and fog lights?

Fog lights have a very short range and should only be used when conditions are…well, foggy. Don’t expect fog lights to serve as your primary light source; these lights are specifically designed to reduce glare from fog, as well as sleet and falling snow.

Is there a law that requires your headlights be on when it’s raining?

Ah, the old “headlights in the rain” law! Is it fact or fiction? Enforced in most states, this headlight law requires all vehicle headlamps be on during inclement weather. Headlight-rain laws vary by state; for instance, drivers in Kansas City, KS, must have headlights on during the day when there’s fog, visibility is less than 1000 feet, or windshield wipers are in use. If they drive across the border and into Missouri, drivers must turn their headlights on when visibility is less than 500 feet.

View your state’s law regarding headlight usage in rain here.

How do I clean my headlights?

A headlight restoration kit is a great place to start, especially if you’re new to car maintenance. For a quick DIY headlight cleaning experience, break out an old toothbrush and a tube of Colgate! Watch this YouTube video for a how-to tutorial on restoring old headlights.


You Might Also Like