Third brake light
SécuritéAverage price
20€ - 400€
The third brake light, also known as the center high-mounted stop lamp (CHMSL), has been a mandatory active safety device on all new vehicles since the late 1990s in Europe. Positioned higher than the main brake lights, usually in the center of the rear window (at the top or bottom) or integrated into a spoiler, its primary purpose is to improve braking visibility for following drivers. This elevated position makes it particularly effective for drivers of taller vehicles (trucks, SUVs) or when the view of the conventional brake lights is obstructed by another vehicle. Initially equipped with halogen bulbs, modern third brake lights almost exclusively use LED technology. LEDs offer near-instant illumination, greater light intensity, and a significantly longer lifespan, thereby enhancing the effectiveness of the warning. By signaling deceleration more clearly and quickly, it significantly reduces the reaction time of the following driver, playing a crucial role in preventing rear-end collisions, one of the most frequent types of accidents.
Benefits
- ✓Significant reduction in the risk of rear-end collisions.
- ✓Increased visibility for following vehicles, especially trucks and SUVs.
- ✓Improved reaction time for other drivers thanks to its elevated position.
- ✓Superior reliability and faster illumination with LED technology.
Learn more
What is the third brake light?
The third brake light, officially known as the 'center high-mounted stop lamp' (CHMSL), is a lighting and safety feature found on virtually all modern vehicles. As the name suggests, it is an additional brake light that illuminates simultaneously with the two main brake lights when the driver presses the brake pedal. Its distinguishing feature is its positioning: it is mounted on the vehicle's centerline, at a higher level than traditional lights. It is most commonly found at the top or bottom of the rear window, or sometimes integrated aerodynamically into a rear spoiler or wing.
A Crucial Role in Accident Prevention
The introduction of the third brake light was not an aesthetic coincidence, but the result of extensive road safety studies. Its main objective is to reduce the incidence of rear-end collisions. By being placed higher up, it is positioned directly in the field of view of most following drivers.
- Better visibility: It is particularly effective in dense traffic. If the vehicle directly behind you blocks your main brake lights for the driver following them, the third brake light remains visible, providing essential braking information.
- Effectiveness for all vehicle sizes: Drivers of taller vehicles such as SUVs, vans, or trucks have a better view of this high-mounted light than of lower lights, which reduces their reaction time.
- Reduced reaction time: Studies have shown that this additional, distinctive light signal captures attention faster, allowing the following driver to gain precious fractions of a second to initiate their own braking.
Technological Evolution: From Halogen to LED
Like many automotive lighting components, the third brake light has benefited from major technological advancements. Initially, it was equipped with incandescent (halogen) bulbs. While functional, they had drawbacks: a noticeable switch-on time, higher energy consumption, and a limited lifespan.
Today, LED (Light Emitting Diode) technology has become the absolute standard for this equipment. The advantages are numerous:
- Instantaneous ignition: An LED reaches full light intensity in a few nanoseconds, compared to about 200 milliseconds for a halogen bulb. At 100 km/h, this difference translates to a braking distance gained of nearly 6 meters for the following vehicle.
- Lifespan: LEDs are designed to last as long as the vehicle itself, reducing maintenance needs.
- Reduced consumption: They consume much less energy, which contributes, on a minor scale, to the vehicle's overall energy efficiency.
- Design flexibility: Their small size allows designers to create thin and complex light signatures, perfectly integrated into the vehicle's styling lines.
Regulations and Maintenance
In Europe, the third brake light became mandatory on all new passenger cars starting October 1, 1998. Its proper operation is therefore imperative. A defective or non-working third brake light is grounds for failure during the mandatory vehicle inspection (MOT/technical inspection). Furthermore, during a roadside check, it can result in a fine for a non-compliant lighting device.
It is therefore essential to regularly check its operation, a simple procedure that can be carried out with the help of another person or by reversing in front of a reflective surface (store window, garage wall). In the event of a failure, replacement is generally straightforward for a bulb-based model, but may require professional intervention for an integrated full LED assembly built into the bodywork.
In conclusion, although it may seem trivial, the third brake light is a simple yet extraordinarily effective safety innovation. It is a silent but vital player in road safety, having proven its role in preventing thousands of accidents every year.
Associated equipment
Automatic headlight activation
Automatic headlight activation is a driver assistance system designed to improve safety and driver comfort. Using a light sensor, usually located on the upper part of the windshield near the rearview mirror, the vehicle detects variations in ambient light. When the light level drops below a predefined threshold, such as at dusk, when entering a tunnel, in an underground parking lot, or during heavy weather, the system automatically commands the activation of the low beam headlights and tail lights. Conversely, when the light level becomes sufficient again, the lights turn off by themselves. This automation frees the driver from any manual intervention, allowing them to focus fully on the road. In addition to ensuring optimal visibility under all circumstances, this device prevents potentially dangerous oversights and avoids fines related to a lack of regulatory lighting. Often coupled with automatic windshield wipers, it is now standard equipment on the majority of new vehicles, actively contributing to active and passive safety.
ESP
ESP, or Electronic Stability Program, is an essential active safety system in modern vehicles, also known as Electronic Stability Control. Its primary role is to keep the vehicle on the trajectory intended by the driver, by preventing loss of grip and skidding. To do this, the ESP uses a series of sensors (wheel speed, steering wheel angle, lateral acceleration, yaw) that continuously analyze the consistency between the direction desired by the driver and the actual behavior of the car. If a discrepancy is detected, signaling the onset of understeer (the front wheels skid) or oversteer (the rear wheels skid), the system intervenes in a fraction of a second. It independently brakes one or more wheels and can also reduce engine power to bring the vehicle back onto the correct trajectory. Mandatory on all new vehicles sold in Europe since 2014, ESP is an electronic guardian angel that significantly increases safety during emergency avoidance maneuvers, in tight corners, or on slippery surfaces (rain, snow, ice). It works in synergy with other aids such as ABS and ASR (traction control).
LED Tail Lights
LED (Light Emitting Diode) tail lights represent a major technological advancement in automotive lighting, gradually replacing traditional halogen bulbs. Unlike the latter, which produce light by heating a filament, LEDs operate through the movement of electrons within a semiconductor material, a process that generates light almost instantaneously and with very little heat production. This technology offers more intense and sharper brightness, significantly improving vehicle visibility for other road users, both day and night. In addition to their primary function (running lights, brake lights, turn signals), LED tail lights have become a distinct design element in their own right. Their small size and flexibility allow manufacturers to create complex and distinctive light signatures, reinforcing a model's visual identity. Their exceptional durability, often equivalent to the lifespan of the vehicle, and their low energy consumption make them an essential standard for active safety and the energy efficiency of modern cars.
Emergency Brake Assist
Emergency Brake Assist (EBA), also known as AFU in French, is an active safety system designed to help the driver achieve maximum braking force in critical situations. This system continuously analyzes the speed and force with which the driver presses the brake pedal. If it detects a rapid and sudden action, characteristic of panic braking, the EBA interprets that the driver intends to stop immediately. It then instantly and automatically increases the pressure in the brake circuit up to the ABS activation threshold, even if the driver has not pressed the pedal to the floor. The primary objective is to compensate for the human reflex of often failing to brake with sufficient force in an emergency. By guaranteeing optimal deceleration from the very first moments, EBA significantly reduces stopping distances, thereby potentially avoiding a collision or drastically reducing its severity. This system works in perfect synergy with ABS (which prevents wheel lock-up) and ESP (which maintains vehicle trajectory), forming an essential trio for modern active safety.
Rear fog lights
The rear fog light is an essential automotive lighting device, specifically designed to improve the visibility of a vehicle from the rear in severely degraded weather conditions. Mandatory on all new vehicles sold in Europe, it consists of one or two lights emitting a very intense red light, significantly more powerful than that of standard tail lights. Its role is not to illuminate the road for the driver, but to signal the vehicle's presence to those following behind, thus allowing them to anticipate its position and speed much earlier than with standard lighting. The activation of the rear fog light is strictly regulated by the Highway Code. It must be used exclusively in the event of fog or heavy snowfall. Its use is prohibited in rainy weather or when visibility is good, because its high brightness can dazzle other drivers, creating a risk of accident. The corresponding indicator on the dashboard, generally orange, informs the driver of its activation. Correct use of this equipment is a guarantee of active security, drastically reducing the risk of rear-end collisions and pile-ups in the most critical visibility situations.