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Illuminating Dirt: Lighting Tech For Four-Wheelers

Posted in How To: Electrical on June 13, 2017
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Photographers: Four Wheeler StaffManufacturers

Humans are, without question, very reliant on our sense of vision. Unlike most mammals, the human sense of smell and our ability to hear is pretty pathetic. Which is to say, in a hypothetical competition you will almost always lose a sense of smell battle to your faithful friend, Fido the trail dog. A bat might be blind, but has hearing that makes us seem like a distracted teen when it comes to listening. The fact is that we are visual mammals, mostly using daytime vision. We use visual communication all the time, and in every day of our lives. According to biologists, the number of rods and cones in the human eye make our daytime vision very good, and our nighttime vision not so great (and we can relate to that). Again, Fido has you beat in nighttime vision acumen. Of course we also have very big brains that are great at problem solving, although you can argue that we are not as smart as we’d like to think we are. One such problem we figured out, just after first playing with fire, was that we could illuminate the dark with a rudimentary torch. Add in a few thousand years of development, and the torch of our cave-dwelling ancestors has been replaced by tools that are much more efficient than a burning stick. We now have lights to illuminate the dirt…frequently in the form of a million (we’re exaggerating a little here) lumen LED lightbar. As a direct result, there are a ton of different lighting options for the sub-species homo sapiens four wheeleriski, a (totally fake) biological group that you probably belong to if you are reading this article.

Night wheeling is a blast, and if you’ve never done it you definitely should. Everything changes, and while you can go night wheeling with very little light on a well-lit full moon evening, headlights, taillights, and off-road lights all make the experience much brighter. Headlights are great, but they can be improved (especially in that old 4x4), and with new advancements in the world of aftermarket illumination there is a lot to be learned about illuminating the dirt. In this story our plan is to cover some of the basics of wiring and illumination to help you better understand how to get the best illumination out of your 4x4 so you can use your innate human superpower (vision) to see farther down the trail.

Proper wiring is critical to light function, and while the vast majority of light companies will provide a switch and wiring harness for your 4x4, there are a few things to keep in mind. Much like with the lights themselves you get what you pay for when it comes to light wiring harnesses. We’re going to talk about how these harnesses work and what to look for when you buy them. Also, our plan is to give you enough information that you could theoretically build your own light wiring harness if you have more time than money or want to be your own head of quality control. Electricity runs in a circle and if there is a break in a wire, positive or negative, whatever you are trying to get to work won’t.

Generally, it’s best to use the largest diameter wire you can, but that has other limitations (like space and the cost of copper). We like to use 18¬–22 gauge wires for signal wires and 12-gauge for power supply, grounds, and feeds when using relays for (relatively) high-amp wiring jobs like aftermarket off-road lights. Handy tools are a soldering iron, wire strippers, wire crimpers, an assortment of wiring terminals, electrical tape, heat shrink tubing (we really like the weatherproof type with some glue that liquefies with heat and seals the connection), and matches or a cigarette lighter.

Shorts happen and can cause extensive damage if not fused properly, jokingly known as letting the smoke out of the wires (it’s basically impossible to get the smoke back into the wires). Damage can range from a burned up wire or two to a vehicle fire causing a total loss. A short is when the wire carrying positive power in your 4x4 comes in contact with any portion of the car that is negatively charged…so in almost all cases, anything metal in the car. This causes a large load of amps to travel through the wire(s) and things can exceed the wire’s amperage rating fast. The end result is the wires will burn…that is unless you have a fuse or fusible link in the circuit. A fuse has a thin piece of metal that is carefully calibrated to melt before any wires or components are damaged. Fusible links are made of special wire that will melt and burn in a specific, easily replaceable area. Everything that uses electricity on your car (with the exception of the starter motor) should have a fuse or fusible link wired inline. Fuses are easy to add to any new wiring, and often vehicles with accessory wires under the dash for use with aftermarket accessories will be fused. Relays will require two fuses, one for the signal (low amp wires) and one for the power supply (higher amp wires).

Most aftermarket lighting companies will sell you a wiring harness that includes terminated wires (with plugs, ring terminals, spade connectors, and the like), a fuse (or fuses), properly sized wire, relay(s), and a switch. This harness from Rigid made installation of some of the company’s aftermarket lights darn right simple. There are ring terminals on the power and ground wire, plugs for the lights, an easily mountable relay, an illuminated switch, and a wiring harness that makes everything work. If you have wire, tools, time, and know-how you could build a harness like this, but these are inexpensive and available.
Inline fuse holders are available at any auto parts store and can be loaded with whatever amp-rated fuse you’d like.
This somewhat antiquated piece of equipment is a fusible link. It’s made to destroy itself if an electrical short occurs. If that happens the link has to be replaced with a new one. Fuses are generally more desirable, but fusible links do an important job on many 4x4s.

Relays are basically electronically controlled switches. To function, a low 1–3 amp signal is sent from a low amp switch inside your 4x4 to the relay (usually mounted underhood). This then closes a switch and supplies higher amperage power to aftermarket lights, or other electronic accessories. Relays keep the high amp circuits out of the passenger compartment, on the engine side of the vehicle’s firewall. That’s good for everyone’s safety. Relays make life for the wires and switches inside the car easier, making it so you can run low amp signal wires to switch on higher amps to accessories on the safe side of your car’s firewall. Relays are very important when maximizing the output of any lighting system. So even though LEDs draw much less amperage than incandescent lights, relays are still a good idea.

Most automotive relays are what’s known as Bosch-style relays. They are available at any auto parts store and can be wired up to handle switching duties of higher amp circuits from under the hood (or outside of the passenger compartment, anyway).

Turning accessories on and off is a task that falls to the electrical switch, and there are many aftermarket switches out there. Many do a good job, and some are cheap pieces of junk. Like with most things you generally get what you pay for, but even we are guilty of using (and abusing) cheap imported parts store switches, and sometimes even with some success.

Switches are generally pretty simple machines that make a mechanical connection or break between two metal posts, allowing electricity to flow through the switch or not. Automotive switches also have different amp ratings that will be dictated by how much amperage is required to run your chosen accessory. Using a switch to send a signal to an underhood relay doesn’t use much amperage, so a lower amp switch is adequate. Running five or six old school incandescent retro round lights on your ’80s K-10 with a triple/double rollbar is going to require a switch (or several) that can deal with the (relatively) high amp draw.

There are many types of switches available in the aftermarket. We’ve had good luck with Carling-style illuminated switches like those that come with ARB Air Lockers and compressors (shown). We’ve also had good luck with K4 brand switches. Many quality switches are sealed to resist dirt and water. That’s good for anyone who uses their 4x4 off-road.

Light emitting diodes, commonly known as LED lights, are incredibly popular for several reasons, including their low energy consumption. They remain cooler during use than other lights, are small in size, have a robust construction and longer life than similar incandescent lights, and fewer environmental concerns upon disposal than other types of lights. LEDs have been in use since the ’60s, but relatively recently saw vast improvements in light production accompanied by a decrease in initial costs.

There is a wide range in prices for aftermarket automotive LED lights, and this is definitely a case of you get what you pay for. Even LED lights that have Cree LEDs may not be very good quality. Cree is a brand name like GM, and while you can buy an inexpensive base model Chevy Spark, it will leave a lot to be desired when compared to a Cadillac CTS-V or loaded Escalade. The same is true for Cree LEDs. There are a litany of other benefits that come from a well-built LED light. LEDs can be built to produce a wide array of colors, but quality LEDs also emit whiter light, mimicking the natural light from the sun that works with our eyes to help us see. It’s cheap and easy to skimp on reflector design, LED attachment, body, electronics, seals, and so on. Cheap Crees hot glued into a cheap reflector attached to a poor quality housing will yield a light that doesn’t work or last as long as one that is extensively engineered and tested.

These LED headlights on a Jeep easily swap in place of the old incandescent bulbs on many vehicles that use a 7-inch bulb. Just install in place of the incandescent bulb and plug the LED light into the factory headlight plug.
Lots of older 4x4s are filled with incandescent bulbs that can easily be swapped out for LEDs that use much less electricity. That’s great, especially when you’re like us and wake up in the middle of the night remembering that you left that one light on.
With a huge range of LED prices know that you will more than likely get what you pay for. Just because a cheap light online comes with Cree LEDs doesn’t mean the housing is sealed well or the reflectors are any good. Trust names you’ve heard like Rigid, KC HiLites, J.W. Speaker, Lazer Star, Vision X, Baja Designs, Lifetime LED, and so on.

These are probably your father’s headlights (unless you are really old, in which case your dad might have used a torch on his wagon). Incandescent light bulbs have been fairly standard on vehicles since the ’60s and electric lights have been on cars since around the beginning of the 20th century. Before that, cars used oil or acetylene gas lamps because early incandescent filaments were too fragile to stand up to the vibrations of automobiles. The incandescent lights you are probably most familiar with are the halogen tungsten sealed beam lights. These lights use a filament made of tungsten that is heated by electricity until it emits a visible glow. The glass or crystal bulb housing is evacuated of air and filled with an inert gas, in this case, halogen. The halogen serves to protect the filament from oxidation and keeps the filament from burning up. Older 4x4s will typically have halogen/tungsten headlights and other incandescent bulbs for turn signals, dash illumination, interior illumination, and more.

Incandescent bulbs are very inefficient and create a fair amount of heat that can be detrimental to their environment (or helpful depending on the application, think lava lamps). They also don’t last as long as LEDs or compact florescent lamps (CFLs) and the filament can be damaged by vibration commonly associated with any vehicles. Also, the bulb itself is generally made of glass, which is relatively heavy and brittle when compared to modern plastics used in other more modern lights. Incandescent lights are definitely on the way out, but still do a job very important to a number of off-roaders around the world.

The old reliable halogen headlight probably isn’t going away just yet. These things are still on all kinds of cars, and they still work, although rather sadly compared to modern lights. They are heavy, prone to cracking or burning out, and old school.
An incandescent bulb like this has powered the parking lights, taillights, interior lights, and much more for many years.
You may have heard of the potato trick to extract a broken light bulb in a lamp in your house, but what should you do if a bulb is broken in a turn signal, running light, interior light, or taillight? Disconnect the negative side of the battery (or you’ll probably pop a fuse) and use needle nose pliers to remove what is left of the bulb.

HID (high intensity discharge)
High intensity discharge (HID) lights use tungsten electrodes housed in a tube filled with an inert gas and metal salts. Electricity causes an arc that produces bright light via the metal salts. HIDs require high voltage and thus require a ballast and sometimes even an igniter to get going. They are more efficient than incandescent and CFL lights, but are generally expensive, and several types of HID lights contain mercury, making special recycling necessary upon light death. Some vehicles come with HIDs from the factory, and for a while several companies offered legally questionable HID retrofit kits to replace incandescent lights. For a while HIDs were the trick to getting very bright off-road lights, but in recent years LEDs have surpassed them and are generally more desirable.

KC HiLites Carbon POD HID light is a HID light we’d love to have. It has a 50W HID ballast, clear or yellow Lexan lenses, a carbon-fiber housing, and produces 5,000 raw lumens. The light is available in a spot or spread (what we would call flood) patterns to illuminate the dirt ahead of you.

Off-Road Lighting Specifics
Almost all cars have lights, and most of the details we’ve covered in this article are not specific to 4x4s, but fairly general to all cars. Our 4x4s get used in very different environments and have specific requirements that we, the four-wheelers of the world, need met. Here are a few off-road specific lighting concerns.

Flood vs. Beam
Depending on if you are going fast or slow off-road you may want lights designed to produce beams of light (for seeing what’s ahead at a distance), or a flood of light (to illuminate the terrain close by). Similar to headlights with low beams and high beams, different aftermarket lights provide different lighting patterns, and very few do both.

Factory incandescent headlights (top) leave something to be desired, but get the job done in a pinch. They do a great job of illuminating a very small part of the trail ahead and do an unremarkable job of generally flooding the trail. Aftermarket LED off-road lights (bottom) do a great job of flooding the trail ahead when compared to the factory headlights alone.

Rock Lights
There was a time 15 years ago when everyone had to have rock lights to illuminate the trail close by during technical rockcrawling. These lights were, and still are, a serious aid when really pushing the limits during night wheeling. Unfortunately, the trend was overdone and adopted by folks who never used the lights as intended and only cared about the “look” it gave their 4x4 (rapidly approaching the hopefully long dead neon under-car lighting scene). LEDs make rock light systems all the easier to install with small lights that are very efficient. So the rock light trend is not dead (despite what many hope), and may never die, but please keep it to a minimum unless you are a proud and true mall crawler.

Rock lights, love them or hate them, do a job. LED technology makes installation a breeze and also keeps energy consumption down if you are on the trail or crawling the mall.

Overlanding/Car Camping Lights
With the ever-growing popularity of overlanding, lights usable for car camping are everywhere. Again, LEDs are great since they are efficient enough to use for hours (if not overnight). Dimmable lights with a flood pattern are the most useful, along with those that can be aimed at food prep surfaces and the like. After all, even though humans don’t have the best night vision in the animal kingdom, nothing ruins your evening enjoyment of the sky faster than a super bright artificial light.

Our friend Randy Ellis built this positionable light to illuminate the cooking surfaces on the back of his well-equipped Chevy Suburban. It uses a KC HiLites LED that doesn’t use much electricity. That’s perfect for overlanding…or car camping.

Mounting lights on a 4x4 is an important part of their function. While it’s trendy to mount them up high, like just below the windshield or above the windshield as with many lightbars, that is not necessarily a good idea. The theory is that the lights are higher and more in line with the driver’s eyes, but often the light illuminates the hood causing glare that makes seeing what’s ahead even harder. We like mounting lights to be where they do the best work and are protected from the trail. That’s usually on the front bumper or grille, but it’s tempting to follow trends even when they don’t make much sense. It’s also important to use a sturdy mount to keep the lights from vibrating. Tabs should be 3/16-inch-thick at a minimum if flat or maybe 1/8-inch-thick if they have bends that make them stronger.

Light tabs should be made of 3/16-inch-thick flat plate or larger or have some bends in the metal to make them strong enough to resist shaking and vibrations. Lightbars are trendy, but we prefer small lights that produce a lot of light mounted to a functional bumper where they are protected from the trail and don’t light up the hood.


KC Hilites
Williams, AZ 86046
Rigid Industries
Mesa, AZ 85215

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