According to the U.S. National Highway Traffic Safety Administration (NHTSA), rear-end crashes account for approximately 1.7 million crashes each year. Distraction alone contributed to 3,208 driving deaths in 2024.
Beyond headlights, taillights, and brake lights, auto manufacturers have introduced other safety features, such as lane departure warning sensors, collision warning systems, rear-view cameras, and more. These features improve visibility and make it easier for following drivers to understand your intentions on the road.
Many drivers still overlook them, compromising their safety, especially when braking or slowing. The end result? Collisions, physical damage, or loss of precious lives.
To prevent collisions and make warning alerts more noticeable, improving brake light visibility matters. This is exactly why the third brake light was introduced.
What is a Third Brake Light & Why Do Vehicles Have It?
Before third brake lights, vehicles had only two standard brake lights mounted at the rear. Researchers found that brake lights effectively indicate braking, but their lower position makes them difficult for drivers to notice, especially in heavy traffic or when a larger vehicle partially blocks the view. To make the stop signal more noticeable and distinct, engineers introduced a third brake light.
The third brake light, officially known as the Center High-Mounted Stop Lamp (CHMSL), is an additional red stop lamp mounted in the vehicle’s centerline above the left and right brake lights. Because they sit in the center, they are also known as a middle or center brake light.
CHMSL activates when you press the brake pedal, illuminating three lights instead of two and giving drivers behind you a clearer signal that your vehicle is stopping or slowing down.
The CHMSL was introduced under Federal Motor Vehicle Safety Standard (FMVSS) No. 108 and has been mandatory on all new passenger cars sold in the United States since the 1986 model year, and on light trucks, SUVs, and vans since the 1994 model year. The regulation requires the lamp to emit red light and remain steadily illuminated during braking.
Position of Third Brake Lights
The position of the third brake light varies by car, its body style, and design. Usually, it's installed inside the vehicle's rear glass. It can be located in the car’s deck lid. On some trucks, the third brake light may be located on the spare wheel carrier.
The third brake light is always installed higher than the two standard left and right brake lights and positioned along the vehicle's centerline. The elevated placement makes it easier for following drivers to notice your intentions on the road, for example, braking or slowing down.
Where third brake lights are positioned differently in different vehicles. Check out the table.
| Vehicle Type | Typical Third Brake Light Position |
|---|---|
| Sedan | Rear windshield |
| Coupe | Rear windshield or spoiler |
| Hatchback | Top of liftgate |
| SUV | Upper liftgate |
| Crossover | Upper tailgate |
| Pickup Truck | Rear cab above the back window |
| Sports Car | Rear spoiler or deck lid |
| Convertible | Trunk lid or rear deck panel |
Why Are Third Brake Lights Important?
Properly installed third brake lights come with several benefits in terms of safety:
Improves Rear Visibility
The primary purpose of a third brake light is to make your vehicle's braking signal more visible to following traffic. Unlike the two standard brake lights mounted lower on the vehicle, the third brake light sits higher and closer to the center, placing it closer to the natural line of sight for drivers behind you.
The elevated position keeps the lights visible from farther away and reduces the chance they'll be hidden by bumpers, cargo, road crests, or other vehicles.
The center-mounted location also helps separate the braking signal from the taillights, making it easier for drivers to recognize that the vehicle ahead is slowing down or stopping.
Whether you're driving during the day, at night, or in adverse weather conditions such as rain or fog, the higher placement improves the overall visibility of your braking signal.
Helps Reduce Rear-End Collisions
Many rear-end collisions happen because following drivers don't recognize that the vehicle ahead is braking until it's too late.
Research conducted by the National Highway Traffic Safety Administration (NHTSA) found that Center High-Mounted Stop Lamps (CHMSLs) reduce rear-end crashes by an average of 4.3% over the long term. The agency estimates this prevents 92,000–137,000 police-reported rear-end crashes and 58,000–70,000 nonfatal injuries every year in the United States.
The third brake light addresses this signal alert more effectively by providing an additional, centrally positioned stop signal that's easier and more prominent than the two lower brake lights alone. When all three brake lights illuminate together, they create a triangular lighting pattern that stands out more effectively than two brake lights by themselves.
The distinctive pattern helps drivers spot braking sooner and react faster, especially in slow traffic where sudden braking is common.
Easier to See in Heavy Traffic
In heavy city traffic, there is a high chance you may not see the vehicle's lower brake lights because you are surrounded by other large vehicles, such as SUVs, pickup trucks, or commercial vehicles.
Third brake lights are mounted higher; they help drivers notice braking earlier in dense traffic, on multi-lane highways, and in closely spaced traffic queues.
The higher-mounted signal also provides better visibility over shorter vehicles and through gaps in traffic, allowing following drivers to react more confidently when traffic suddenly slows.
Provides Backup if One Brake Light Fails
Although the third brake light is not designed to replace the left or right brake lights, it can serve as an additional braking-signal warning light for following traffic if any standard brake light bulb stops working.
However, keep in mind that third brake lights can never replace a faulty brake light. A failed brake light can reduce overall visibility, compromise compliance with state vehicle regulations, and increase the risk of a rear-end collision.
Situations When Third Brake Light Requires the Most
Although third brake lights provide sufficient visibility in all driving conditions, their benefits are more noticeable when drivers have less time or visibility to react. Some of the most common scenarios include:
- Stop-and-go traffic
- Highway driving at higher speeds
- Heavy rain, fog, or snowfall
- Nighttime driving
- Dense multi-lane traffic
- Following large SUVs, pickup trucks, or commercial vehicles
- Vehicles following too closely (tailgating)
- Roads with hills, inclines, or crests
- Poorly lit roads and highways
- Emergency or sudden braking situations
Third Brake Light Not Working: Common Problems and Early Signs
When the third brake light of your car doesn’t work, it can increase your chances of being part of a rear-end accident.
The light can stop working for multiple reasons. Like any exterior light, a 3rd brake light may be exposed to heat, moisture, vibration, and everyday wear, which can cause LED chips to fail, a fuse to blow, and wiring to be damaged. Recognizing these early signs below can help prevent complete brake light failure.
- Third brake light not illuminating
- Flickering while braking
- Dim or uneven brightness
- Intermittent operation
- Dashboard brake light warning
- Moisture or condensation inside the lens
- Cracked or damaged lens
Why Choose LED Bulbs for Third Brake Light?
If your third brake light isn't working, it's a great time to upgrade to LED lights. You won’t need more than a couple of minutes to upgrade the brake light. Just locate the third brake light housing and open it with a screwdriver. Remove the old bulb from the socket; adjust the wiring and reattach the housing.
Smaller LED bulbs use less power and require less maintenance. They also light up faster, which is ideal for a third brake light because it notifies other drivers immediately.
More Durable
You may want to stick with traditional halogen bulbs, but remember that LED third brake lights are more durable. An LED bulb lasts at least three times longer than halogen bulbs.
Brighter than Other Options
Do you think LED headlights are useful, but LED third brake lights may be taking things a bit too far? LEDs are brighter than other options on the market. This means other drivers can see your car more clearly when you brake.
Affordable
Today, you can get LED third brake lights for $50 or less. They aren't as expensive as they used to be. Plus, because they last longer, LED brake lights have low operating costs.
Looking to upgrade third brake lights that meet Department of Transportation (DOT) standards? Underground Lighting offers the best quality LED 3rd brake light for all makes and models. Get in touch with us today. We sell a large variety of HID replacement bulbs, LED conversion kits, and all types of car lighting products to give you the car you deserve.
Is It Illegal to Drive Without a Third Brake Light?
In most cases, yes—if your vehicle was originally equipped with a third brake light, it is generally expected to remain functional. Third brake lights, officially known as Center High-Mounted Stop Lamps, are required under Federal Motor Vehicle Safety Standard (FMVSS) No. 108 on all new passenger cars since the 1986 model year and light trucks, SUVs, vans, and multipurpose passenger vehicles since the 1994 model year.
Although FMVSS 108 regulates vehicle manufacturers rather than drivers, many states require all factory-installed lighting equipment, including the third brake light, to be operational.
Depending on your state's vehicle code and inspection requirements, driving with a non-functioning or missing third brake light may result in a failed safety inspection, a fix-it notice, or a traffic citation. Since enforcement varies by state, check your local regulations and replace a faulty third brake light as soon as possible.
Conclusion
A third brake light is more than an additional light—it is an important safety feature that helps following drivers recognize when your vehicle is slowing down or stopping. Keeping it bright, functional, and properly installed can improve visibility and reduce the risk of rear-end collisions. If your third brake light is flickering, dim, or not working, replace it promptly with a reliable LED bulb to keep your vehicle safer on the road.
