What Is the Brake Light in the Middle Called?
The brake light in the middle at the rear of a vehicle is officially called the Center High-Mounted Stop Lamp (CHMSL), commonly known as the third brake light or high-level brake light. It is an additional brake light placed higher than the main left and right brake lamps to improve visibility and safety.
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Understanding the Center High-Mounted Stop Lamp (CHMSL)
When people refer to “the brake light in the middle,” they are usually talking about the red light mounted at the center of the vehicle’s rear—often on the trunk lid, tailgate, or at the top of the rear window. This light is synchronized with the other brake lights and illuminates whenever the driver presses the brake pedal. Its primary role is to make the vehicle’s braking more noticeable, especially to drivers who are following closely or whose view of the lower brake lights might be partially blocked.
Official Name vs. Common Names
In automotive regulations and technical documentation, the proper term is “Center High-Mounted Stop Lamp,” abbreviated as CHMSL. Outside regulatory and engineering circles, everyday drivers and mechanics typically use more informal names that refer to its position and function.
- Center High-Mounted Stop Lamp (CHMSL) – The official, regulatory name used in safety standards and by manufacturers.
- Third Brake Light – The most common colloquial term, reflecting that it supplements the two main left and right brake lamps.
- High-Mount Brake Light – Emphasizes that it is mounted higher than the regular brake lights.
- High-Level Brake Light – Similar to “high-mount,” used frequently in European and international contexts.
- Center Brake Light – A general descriptive term highlighting its central position.
The following list explains the most common names you might hear for the middle brake light and what they mean.
Together, these names all describe the same safety component, with CHMSL as the formal designation and “third brake light” as the term most drivers recognize.
Why the Third Brake Light Exists
The third brake light was not always a standard feature. It became widespread after safety researchers and regulators found that adding a centrally mounted, higher-positioned brake light significantly reduced rear-end collisions by making braking intentions clearer to drivers behind.
Safety and Visibility Benefits
Placing a brake light higher in the driver’s line of sight improves the chances that other motorists will notice when a vehicle is slowing down, particularly in heavy traffic or when taller vehicles partially block the view of the lower lights.
- Improved visibility in traffic – A higher light is easier to see over the roofs of other vehicles, especially for drivers following at a distance.
- Faster reaction times – Research has shown that drivers tend to react more quickly when there is a distinct, central brake signal, reducing stopping distances.
- Better performance in bad weather – In rain, fog, or spray, the elevated lamp can be less obscured than lower-mounted lights near the bumper.
- Redundancy for safety – If one of the main brake lights fails, the third brake light still provides a clear signal that the car is braking.
- Clearer communication in dense traffic – The central lamp is often the most visible element when vehicles are close together, such as in stop-and-go conditions.
The following points highlight the main safety and visibility reasons for the CHMSL’s adoption.
These combined benefits mean the third brake light functions as an extra layer of visual warning, enhancing overall road safety.
Legal Requirements and Regulations
Today, the center high-mounted stop lamp is mandatory equipment on most modern passenger vehicles in many countries, including the United States and across the European Union, with specific rules governing its placement, brightness, and color.
Adoption in Different Markets
Though the exact timelines and rules vary among regions, regulators worldwide have broadly agreed on the effectiveness of the third brake light as a straightforward, cost-effective safety measure.
- United States – The National Highway Traffic Safety Administration (NHTSA) first required CHMSLs on new passenger cars starting with the 1986 model year, later extending the requirement to light trucks and vans (starting around the 1994 model year). The light must be red, centered, and mounted higher than the other stop lamps.
- European Union – Under UNECE regulations (notably Regulation No. 7 and others), most passenger vehicles sold in EU member states have long been required to include a high-mounted stop lamp, with specific rules for height, angle, and luminous intensity.
- Other regions – Many countries in Asia, Latin America, and elsewhere have adopted similar standards, either by referencing UNECE regulations or setting national rules that closely mirror them.
- Aftermarket and retrofitting – In some jurisdictions, older vehicles that predate the requirement can legally add an aftermarket third brake light, provided it meets color and wiring standards and does not confuse other signals.
The following overview outlines how regulations for the CHMSL have developed in key markets.
Taken together, these regulatory steps have made the CHMSL a near-universal feature on contemporary vehicles, reinforcing its role as a global safety standard.
Design, Position, and Technology
Although the function is consistent, the appearance and mounting location of the third brake light can vary with vehicle type and design trends. Advances in lighting technology have also changed how these lamps are built and integrated into vehicle styling.
Typical Mounting Locations
Manufacturers position the CHMSL where it can be easily seen by following drivers and protected from damage, while fitting within the vehicle’s design language.
- Top of the rear window – Often in sedans, hatchbacks, and some SUVs, integrated into the headliner or roofline above the glass.
- Within the rear window – Mounted on the rear parcel shelf (the interior ledge under the rear window) or attached to the glass itself.
- On the trunk lid or tailgate – Common in sedans and liftbacks, with the lamp located at the upper edge of the trunk or integrated into a rear spoiler.
- Integrated into a rear spoiler – Especially on sportier models, the third brake light can be built into a small spoiler on the trunk or roof.
- On vans and taller vehicles – Frequently placed at the very top of the rear doors or bodywork to maximize visibility from farther back.
The following are the most common places you’ll find the center high-mounted stop lamp on modern vehicles.
Despite the different mounting points, the unifying requirement is that the lamp is centrally located, clearly visible from the rear, and higher than the primary brake lights.
Lighting Technology: From Bulbs to LEDs
The third brake light has followed the broader industry transition from incandescent bulbs to LEDs, bringing durability and styling advantages along with improved efficiency.
- Incandescent bulbs (older designs) – Early third brake lights used conventional bulbs similar to other exterior lamps, requiring periodic replacement and larger housings.
- LED (light-emitting diode) systems – Today, most CHMSLs are LED-based, offering quicker illumination—critical for reaction time—along with a longer service life and lower power consumption.
- Light bars and signature designs – Many newer models use continuous LED light bars or stylized clusters that double as design elements, making the vehicle more recognizable when braking.
- Integrated electronics – Modern CHMSLs often include sealed units with integrated circuitry, increasing reliability but typically requiring full-unit replacement if they fail.
- Smart signal concepts (emerging) – Some experimental systems explore variable-intensity or animated brake signals, though regulations still generally require a simple, steady red light when braking.
The following breakdown illustrates how CHMSL lighting technology has evolved and what most modern cars now use.
This evolution in hardware has helped make the third brake light more reliable and visually prominent, strengthening its role as a key communication signal on the road.
Maintenance, Inspection, and Legal Responsibility
Even though the third brake light is small, it is legally treated like any other critical safety device. Drivers are generally required to keep it in good working order, and a malfunctioning CHMSL can lead to inspection failures or traffic stops in some jurisdictions.
Checking and Caring for the Third Brake Light
Because it is positioned high and sometimes embedded in bodywork or glass, the CHMSL can be easy to overlook during routine checks. Regular inspection helps ensure that other road users always see your braking signals clearly.
- Regular function check – Periodically have someone press the brake pedal while you stand behind the vehicle to confirm the third brake light illuminates alongside the main brake lamps.
- Inspect for cracks or condensation – Damage to the housing or water inside the lens can shorten the life of the light and reduce its brightness.
- Clean the lens – Dirt, road film, and tint overspray (if illegally applied) can dim the light output; a clean, clear lens maximizes visibility.
- Bulb or unit replacement – On older cars, a failed incandescent bulb can often be replaced individually. On newer LED units, the entire lamp assembly may need replacement if it fails.
- Check wiring and connections – If the light does not work even with a new unit, a blown fuse, broken wire, or loose connector may be the cause and may require professional diagnosis.
The following practical steps and considerations can help keep the center high-mounted stop lamp functioning properly.
Keeping the third brake light in good condition is a simple but vital part of vehicle maintenance that directly affects how clearly your braking intentions are communicated to other drivers.
Summary
The brake light in the middle of the back of a vehicle is formally known as the Center High-Mounted Stop Lamp (CHMSL) and is popularly called the third brake light or high-level brake light. Positioned higher and centrally at the rear, it activates with the regular brake lights and is designed to make braking more conspicuous to following drivers. Now a legal requirement on most modern vehicles worldwide, the CHMSL has been shown to reduce rear-end collisions by improving visibility, especially in dense traffic and poor weather. With modern LED technology and careful placement, this relatively small component plays an outsized role in everyday road safety, making it essential to keep it clean, functional, and well maintained.
Does the 3rd brake light have to work?
Yes, in most places, the third brake light is legally required to work, though specific state inspection rules can vary. It has been mandatory on new passenger cars since 1986 and on new light trucks since 1994, and it is a violation of federal law to have it out. Driving with a non-functional third brake light can lead to being pulled over, failing a safety inspection, or being at a higher risk of being rear-ended.
Why it’s required
- Safety: The third brake light, or Center High Mounted Stop Lamp (CHMSL), is designed to be more visible to following drivers, which helps reduce rear-end collisions.
- Federal law: Federal regulations mandate that new vehicles must be equipped with a CHMSL.
- State inspection: Many states require all factory-installed equipment to be functional, meaning a third brake light must pass a safety inspection if the vehicle is equipped with one.
Consequences of a non-working light
- Traffic stop: You can be pulled over by law enforcement for a burnt-out light, as it is a violation of the law.
- Inspection failure: Many states require that all lights on the vehicle be in good working order to pass a safety inspection.
- Increased accident risk: A non-working third brake light eliminates a key safety feature, increasing the likelihood of a rear-end collision.
Is it illegal to drive without a center brake light?
All lights must work. It’s an equipment violation.
What is the purpose of the 3rd brake light?
Experts say it helps prevent rear end collisions. Tests done by installing the third brake light in taxis and fleet vehicles showed fewer rear end crashes in the ones that had the extra light. The third brake light was mandated in new passenger cars in 1986 in the US and Canada.
What is the 3rd brake light bulb?
The third brake light, also known as the center high mount stop lamp (CHMSL), is a crucial safety feature located at the rear center of a vehicle.
