What trailer clearance lights are and where they go

Clearance lights are small marker lights mounted on the sides and top corners of a trailer to show its width and height to other drivers, especially at night or in poor visibility. They are not brake lights or turn signals — they stay on whenever your trailer lights are powered, whether you are moving or parked.

On most trailers, you will find clearance lights in three locations: one on each upper front corner (showing the width of the trailer front), one on each upper rear corner (showing the width at the back), and sometimes one on top center if the trailer is tall enough. Some trailers also have side marker lights running along the length, which serve the same purpose — marking the trailer's outer edges so other drivers know how much space it takes up on the road.

Clearance lights are required by law on trailers wider than 80 inches or taller than 13 feet. If your trailer is smaller than those dimensions, clearance lights are not legally required, though many owners install them anyway for safety.

Key Takeaways

  • Clearance lights mark the width and height of your trailer so other drivers can judge its size, especially in darkness or fog.
  • They are required on trailers wider than 80 inches or taller than 13 feet, and must be amber on the front and red on the back.
  • Clearance lights stay on whenever your trailer is connected and powered, separate from brake lights and turn signals.
  • Most clearance lights use LED bulbs now, which draw less power and last longer than older incandescent types.
  • A burned-out clearance light is a safety hazard and can result in a traffic citation in most states.

Color requirements and legal standards

Clearance lights must follow specific color rules set by the Department of Transportation. The front clearance lights must be amber (yellow-orange), and the rear clearance lights must be red. This color coding tells other drivers which end of the trailer they are looking at, especially important on dark highways where the trailer outline might be hard to see.

The lights must also meet brightness standards — they need to be visible from at least 500 feet away in normal darkness. This is why a single burned-out bulb matters: it breaks the outline and makes the trailer harder to judge. Most states treat a missing or non-functioning clearance light as a safety violation, and you can receive a citation if a law enforcement officer spots it during a traffic stop or inspection.

The exact wiring and connector type varies by trailer age and manufacturer, but modern trailers typically use a standard four-pin or seven-pin connector that carries power to all lights at once. When you plug your trailer into your vehicle's hitch connector, power flows to the clearance lights through that same circuit.

How to check if your clearance lights are working

The simplest check is to connect your trailer to a vehicle, turn on the trailer lights (usually via a switch on your dashboard or by turning on your headlights), and walk around the trailer in daylight to see if all the lights glow. You should see amber lights at the front corners and red lights at the rear corners. If any light is dark or dimmer than the others, the bulb likely needs replacement.

At night, the check is even easier — the lights will be much more visible. Have someone sit in the vehicle while you stand in front of and behind the trailer to confirm all lights are on. If you see a gap in the light pattern, note which corner or side is dark.

If a light does not come on, the problem is usually a burned-out bulb, a loose connector, or a blown fuse in the trailer's wiring harness. Most trailers have a fuse block mounted inside or underneath, often near the hitch. Check your trailer manual for the fuse location and amperage rating before replacing one.

Replacing a burned-out clearance light bulb

Most clearance light housings are held in place by two or three small bolts or screws on the outside of the trailer. Unbolt the entire light assembly — do not try to reach inside and twist the bulb while the housing is still mounted, as you risk breaking the lens or the socket.

Once the housing is off, you will see the bulb socket inside. Twist the socket counterclockwise (or pull it straight out, depending on the design) to remove it from the housing. The bulb itself usually twists out of the socket. Note the bulb type — most clearance lights use a 194 or 168 bulb for incandescent, or a corresponding LED equivalent if your trailer has been upgraded.

Buy a replacement bulb of the same type and wattage. LED bulbs are now standard on new trailers and are worth installing on older trailers because they draw less power from your vehicle's electrical system and last far longer. Twist the new bulb into the socket, push or twist the socket back into the housing, and bolt the housing back onto the trailer. Test the light before you drive.

Wiring and power supply issues

If multiple clearance lights are out, or if replacing the bulb does not fix the problem, the issue is likely in the wiring or power supply rather than the bulb itself. Start by checking the connector where your trailer plugs into your vehicle. Look for corrosion, bent pins, or loose wires. If the connector looks dirty or corroded, unplug it, clean both sides with a dry cloth or fine-grit sandpaper, and plug it back in.

Next, check the fuse in your trailer's fuse block. A blown fuse will cut power to all lights on that circuit. If the fuse is blackened or the wire inside is broken, replace it with one of the same amperage. If the fuse blows again when ready after replacement, there is a short circuit somewhere in the wiring, and you should have a trailer technician inspect the harness.

If the connector and fuse are both fine, the problem may be a broken wire inside the trailer's harness, a corroded ground connection, or a faulty light socket. These issues require opening up the trailer's wiring, which is best left to someone with experience in trailer electrical systems.

Maintenance to prevent clearance light problems

Clearance light failures are usually preventable with basic maintenance. After each use, visually inspect all four corners of your trailer for cracks in the lens or water inside the housing. Water inside means the seal has failed and moisture will corrode the socket and bulb. If you see water, remove the housing, dry it out completely, and replace the bulb and socket if they show any corrosion.

Once or twice a year, unplug your trailer and inspect the connector pins for corrosion. If you see any green or white buildup, clean it with a dry cloth or a contact cleaner made for electrical connectors. Reapply a thin coat of dielectric grease to the pins before plugging back in — this prevents moisture from corroding the connection.

If your trailer sits unused for months, check the clearance lights before you tow it. A bulb that was fine in storage may have failed from vibration or age, and you want to catch that before you are on the highway.

LED upgrades and modern alternatives

Many older trailers came with incandescent clearance lights that draw significant power and burn out frequently. Upgrading to LED clearance lights is straightforward and worth the investment if your trailer is more than five years old. LED bulbs use about one-tenth the power, last 10 to 20 times longer, and are brighter in daylight, making your trailer more visible.

LED upgrades come in two forms: direct replacement bulbs that fit into your existing sockets, or complete new light assemblies with integrated LEDs. Direct replacement bulbs are cheaper and faster to install — you straightforward remove the old bulb and twist in the LED version. Complete assemblies cost more but often include improved weatherproofing and a modern look.

When buying LED replacements, make sure they are DOT-approved and rated for the correct color (amber for front, red for rear). Some cheap LED bulbs do not meet brightness standards and will not pass inspection. Check the product description or ask the seller whether the bulbs meet Department of Transportation requirements.

Frequently Asked Questions

Do clearance lights stay on all the time or only when I am towing?

Clearance lights only come on when your trailer is connected to a vehicle and the trailer lights are powered. They turn off when you disconnect the trailer. If your trailer is parked and not connected, the clearance lights will not be on, even if the sun is down.

Can I use white or clear bulbs in my clearance lights instead of amber and red?

No. Federal law requires amber on the front and red on the rear. Using the wrong color is a safety violation and can result in a citation. The colors are standardized so other drivers when ready know which end of the trailer they are looking at.

What happens if I drive with a burned-out clearance light?

You risk a traffic citation if a law enforcement officer spots it during a traffic stop or roadside inspection. More importantly, other drivers lose part of the visual outline of your trailer, especially at night, which increases the risk of a collision. Replace burned-out lights before you tow.

Do I need clearance lights on a small utility trailer?

Only if your trailer is wider than 80 inches or taller than 13 feet. Most small utility trailers fall below those thresholds and do not require clearance lights by law. However, adding them anyway is a good safety choice, particularly if you tow at night.

Can I install clearance lights on a trailer that did not come with them?

Yes. You can buy aftermarket clearance light kits designed to bolt onto trailers. Installation requires drilling holes, running wiring to the trailer's power connector, and possibly adding a fuse block if your trailer does not have one. If you are not comfortable with electrical work, a trailer shop can install them for you.