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HomeTips & GuidesSealed Beam Headlight Wiring: All You Need to Know

Sealed Beam Headlight Wiring: All You Need to Know

About sealed beam headlight wiring. Welcome to this guide, where we leave no stone unturned on auto headlight wiring. A dim, faulty, or malfunctioning headlight resembles the proverbial running in the dark. 

So today, we bring you insights on how to ensure your sealed beam headlight shines brightest. We’ll also show you how to install it quickly, so read on to the end for all these details. 

What Are Sealed Beam Headlights?

It is a headlight system comprising the lighting filament, a reflective casing, and the lens in one package. The setup ensures that the headlight has optimal illumination, making it crucial during night drives. 

The sealed beam headlight is part of the vehicle’s wiring system. Hence, for the best performance, you must have perfect wiring. So, how did this wiring come to exist? It was first invented in the 1940s, a move that was key to improving the car’s lighting system. 

Even with its invention, the system’s brightness and lifetime were less optimal than today’s lights. Over the years, the sealed beam headlights have undergone massive improvements, ensuring they are excellent. Also, today, you can easily replace one if it is damaged.  

Why Buy Sealed Beam Headlights?

Headlights on construction machinery. 

Headlights on construction machinery. 

Among the upsides of the modern-day sealed beam headlights include the following: 

  1. They have extensive longevity and feature a one-piece design that makes installation easy. 
  2. Secondly, they are cheap to buy and run because they don’t consume much power.

However, they also have some downsides worth looking at before buying this lighting unit. 

  1. First, their design is the same in all cases, so you cannot be flexible in designing/customizing your lights. 
  2. Conventional sealed beam headlights consume more power than modern LED lights. Old-school beamlights have a tungsten filament, which consumes more energy. 
  3. Lastly, repair is simple because you only replace the entire unit. It can balloon the replacement costs compared to other lighting units where you only replace the bulb. 

Essential Components Of A Sealed Beam Headlight System

A tractor headlight. 

A tractor headlight. 

The seamless beam headlight system is simple in makeup and comprises just the following parts: 

  • First, there is the headlight bulb featuring a filament, which is the light source in the system. The illumination source is irresponsible for giving out light to enable visibility while driving in the dark. 
  • Also, there is a reflector, which is usually the interior casing of the system. It is responsible for directing the light uniformly for excellent illumination. 
  • The lens is the bulb’s protector and contributes to directing/reflecting the light. 
  • Moreover, there is the bulb casing/housing, which is the outer cover of the unit that you connect to the headlight slot. 
  • The system also features wires running from the bulb to the car’s battery, the power source. 
  • Finally, there’s the wiring harness, a network of wires that the headlight bulb is part of and helps protect the wires. 

Step-by-step Guide To Wiring Sealed Beam Headlights

Assemble the Tools

Flathead and Philipshead screwdriver. 

Flathead and Philipshead screwdriver. 

Start by assembling the tools you need for the installation. You will require the following: 

  • A flathead and a Philip’s head screwdriver. 
  • Wires long enough and of the proper gauge depending on your headlights’ rating.
  • Wire stripper. 
  • A sealed beam headlight. If you’re replacing one, it’s recommended that you use one with a rating similar to the one you’re removing. 
  • Wire Crimpers and Electrical Tape
  • Wiring diagram. This one will depend on your car’s model, so consult your wiring diagram.

Connect the Wiring and Headlights

An old tractor’s headlights. 

An old tractor’s headlights. 

Once these parts are secured, you can set the sealed wiring beam headlight. 

  1. The first thing is to ensure that you operate safely. So remove the negative battery terminal and ensure your repair areas are well-lit. 
  2. Moreover, ensure your car’s wiring diagram is available, as it will help you identify where to connect each wire. You must also don protective wear such as safety glasses. 
  3. Next, remove the old headlight by unscrewing it from the holding hood. Next, remove the old wiring harness that provided power to the headlights. At the exact location, lay the wiring for the new headlight and secure the wires with electrical tape or clips. 
  4. Remember that your car’s wiring diagram is your ultimate guide when making the connections. Therefore, consult it and connect each wire according to the guide. If necessary, you may solder the wires at the junction where they join the headlight terminals. 
  5. Now, choose headlight connectors of the right size and connect the wires from the harness to them. Connect the connectors to the headlight and ensure the connection is tight and robust. We caution against touching the glass part of the headlight, as you may introduce stains. 
  6. If everything is perfectly connected, restore the battery connections and switch on the light to test it. If it lights up brightly, you’ve installed everything perfectly. Now you can screw the headlight onto its casing using the screwdrivers. 

Troubleshooting Common Issues In Sealed Beam Headlight Wiring

A very old sealed beam headlight. 

A very old sealed beam headlight. 

When your sealed beam headlights are not working, it can sometimes be daunting to tell where exactly the problem is. The wiring is complex, which is why diagnosis can be challenging. 

But with the following tips, everything is a breeze. 

  1. Most of the issues are electrical, so check the car fuses. Are they in good shape? A blown fuse will affect the entire lighting system, so identifying it can save you the hassle of looking for the issue elsewhere. 
  2. Next, check if there are problems with the headlight connectors. Ensuring a fully charged battery is the most important thing in this case. If the voltage is low, the headlights will bear the brunt. Hence, you may not know if the issue is the contacts or battery. 
  3. How about when your sealed beam headlight lights up only dimly? In this case, we recommend checking out the wire connections. Often, cables will tear, cut, or loosen due to the car’s vibrations.
  4. Don’t insist on doing it all by yourself, especially if you lack the professional nous to handle car wiring. The car harness is a special wiring that even the typical electrician may struggle to crack. So, if the basic diagnostic measures are futile, involve a car mechanic to locate the issue. 
  5. Also, we don’t want you to wait until the problem has happened before investigating/fixing it. Regular inspections will save you a lot of problems. Also, regular maintenance practices such as greasing the contacts should be habitually performed.
  6. Finally, only use like-for-like replacements when fixing sealed beam headlight wiring issues. 

Sealed Beam Headlights versus Modern Headlight Systems

A modern car headlight. 

A modern car headlight. 

The car lighting industry has evolved quickly over the years. Today, we have better and more efficient lights than sealed beam headlights. While these lights have the swagger of being an all-in-one unit, their efficiency is quite a problem compared to others. 

For instance, halogen headlights have better energy efficiency and exceptional brightness. But these are just not the only upgrades on old-school sealed beam headlights. We also have Inert gas lights such as HIDs/Xenon Lights and light-emitting diodes (LEDs)

The two offer better brightness and longer runtime than conventional sealed beam headlights. 


If you don’t get the car lighting right, you will be in trouble because this is one of the most crucial functionalities. Today, we’ve guided you through one of the most essential car lighting systems.

The most important thing is getting the wiring and regular maintenance to improve its lifetime. 

I am Lillian Yang, having been a sales manager for over 10 years.

I have received many positive reviews from customers. They have praised our excellent service, on-time delivery, and high-quality cable assemblies.

For your projects, please provide cable assembly files/images/smples, etc., so that I can send you a quotation within 24 hours.

Contact me now and let’s get started on building your wire harnesses!

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