Truck clearance lights mark the outer edges and height of your vehicle
Clearance lights are small lights mounted on the top corners and sides of a truck to show other drivers where the vehicle's edges and highest points are. On most trucks, you'll find them on the roof near the front corners, along the sides, and sometimes at the rear. They're especially important at night or in poor visibility, when the truck's full size isn't obvious to other drivers.
These lights serve a safety function: they help prevent collisions with other vehicles, low-hanging obstacles like tree branches or bridge overhangs, and other hazards that depend on drivers knowing exactly how wide and tall your truck is. Clearance lights are required by law on certain vehicles, though the specific requirements vary by state and by the truck's size and weight.
The lights themselves are usually amber or red, depending on their location on the truck. Front and side clearance lights are typically amber, while rear lights are red. They're wired to turn on whenever your headlights or parking lights are on, so they're visible whenever other drivers need to see your truck's outline.
Key Takeaways
- Clearance lights show the width and height of your truck to other drivers, especially in darkness or poor visibility.
- Federal law requires clearance lights on trucks over a certain width or height, but state regulations vary on which trucks need them.
- Front and side clearance lights are amber; rear clearance lights are red.
- Clearance lights must work whenever your headlights or parking lights are on, and burned-out bulbs should be replaced promptly.
- Clearance lights are different from marker lights and side-marker lights, which serve similar but distinct purposes.
Federal requirements for clearance lights
The Federal Motor Carrier Safety Administration (FMCSA) requires clearance lights on trucks that are wider than 80 inches or taller than 102 inches. If your truck meets either of these measurements, you must have clearance lights installed and functioning. The FMCSA also requires that these lights be amber on the front and sides, and red on the rear.
Trucks that don't meet these size thresholds may still be required to have clearance lights under state law, so you should check your state's regulations even if your truck is smaller. Some states have stricter requirements than the federal standard, and some require clearance lights on all commercial trucks regardless of size.
The lights must be visible from at least 500 feet away in normal darkness, and they must be wired so they come on automatically with your parking lights or headlights. If a clearance light burns out, it should be replaced as soon as possible—driving with a burned-out clearance light may result in a citation in some states.
Where clearance lights are mounted on a truck
On most trucks, clearance lights are mounted in pairs on the roof, one near each front corner. These front clearance lights are amber and help oncoming traffic see the truck's width and height. Side clearance lights run along the length of the truck's body, also in amber, and mark the outer edges of the vehicle.
Rear clearance lights are mounted on the back of the truck or trailer, usually on the upper corners, and are red. Some trucks also have clearance lights mounted lower on the sides, between the front and rear wheels, to mark the truck's profile along its entire length.
The exact placement depends on the truck's design and the state's regulations. If you're unsure whether your truck has all the clearance lights it needs, your state's Department of Transportation or a commercial truck inspection station can tell you what's required for your specific vehicle.
Clearance lights versus marker lights and side-marker lights
Clearance lights, marker lights, and side-marker lights are often confused because they serve related purposes, but they're not the same thing. Marker lights are small lights that mark the corners or edges of a vehicle and are required on all trucks over a certain length. Side-marker lights are specifically the lights mounted on the sides of the truck between the front and rear wheels.
Clearance lights show the truck's overall width and height, while marker lights and side-marker lights show its length and profile. A truck may have all three types of lights, and they all serve to make the vehicle visible to other drivers. The color and placement of each type are regulated separately, so it's possible for a truck to have clearance lights but not marker lights, or vice versa, depending on its size and the state's rules.
If you're not sure which lights on your truck are which, a truck inspection station or your truck's manual can clarify. Knowing the difference matters if you need to replace a bulb or troubleshoot a lighting problem.
Checking and maintaining clearance lights
Clearance lights should be checked regularly to make sure they're working. The easiest way to do this is to turn on your parking lights or headlights at dusk or in a dark area, walk around the truck, and look for any lights that aren't lit. If you find a burned-out bulb, note which light it is and replace it with the correct bulb type for that location.
Most clearance light bulbs are standard automotive bulbs that you can buy at any auto parts store. The bulb type depends on the light's location and the truck's model year, so check your truck's manual or ask at the parts store for the right replacement. Some clearance lights are sealed units that require the entire fixture to be replaced rather than just the bulb, so if you're not sure how to replace a bulb, a mechanic can do it quickly.
If multiple clearance lights aren't working, the problem may be a blown fuse or a wiring issue rather than burned-out bulbs. Check your truck's fuse box to see if the clearance light fuse has blown, and replace it if needed. If the fuse keeps blowing or the lights still don't work after replacing it, have a mechanic inspect the wiring.
State-specific clearance light rules
While federal law sets the baseline for clearance lights on trucks over 80 inches wide or 102 inches tall, individual states can impose stricter rules. Some states require clearance lights on smaller trucks, or require them to be a different color or brightness than the federal standard. A few states also have specific rules about when clearance lights must be on—some require them whenever the truck is in operation, not just when headlights are on.
Before you buy or modify a truck, check your state's Department of Transportation website or contact a local commercial truck inspection station to learn what's required where you drive. If you cross state lines regularly, you'll need to meet the requirements of every state you travel through, which usually means meeting the strictest standard among them.
Frequently Asked Questions
Do I need clearance lights if my truck is under 80 inches wide?
Federal law doesn't require them, but your state may. Check your state's Department of Transportation rules or contact a truck inspection station. Some states require clearance lights on all commercial trucks regardless of size, while others follow only the federal standard.
What should I do if a clearance light burns out?
Replace the bulb with the correct type for that location, which you can find in your truck's manual or at an auto parts store. If the bulb is part of a sealed fixture, the entire fixture may need to be replaced. If multiple lights are out, check the fuse first before replacing bulbs.
Can I drive with a burned-out clearance light?
Technically you can, but it's not safe and may result in a citation. A burned-out clearance light reduces visibility of your truck's size and height to other drivers, increasing the risk of collision. Replace burned-out bulbs as soon as possible.
Are clearance lights the same as running lights?
No. Running lights (or daytime running lights) are forward-facing lights that improve visibility during the day. Clearance lights mark the truck's edges and height and are required to be on whenever parking lights or headlights are on. They serve different purposes and are wired separately.
What color should clearance lights be?
Front and side clearance lights must be amber. Rear clearance lights must be red. These colors are set by federal regulation and help other drivers quickly identify which part of the truck they're looking at, especially in darkness.