The 3rd brake light is formally called the Center High Mount Stop Lamp (CHMSL), and in everyday speech it’s simply known as the third brake light.
Understanding the terminology
In automotive terminology, the term “third brake light” describes a third stop signal located higher than the two tail lights. The official designation used by regulators in many regions is Center High Mount Stop Lamp (CHMSL), with minor regional spelling variations such as “Centre High Mount Stop Lamp.”
Regional variations
Different markets use slightly different names. Common terms include CHMSL in the United States, and Centre High Mounted Stop Lamp in British/Commonwealth contexts. Some people still refer to it simply as the third brake light or center brake light. Manufacturers may also integrate the light into a spoiler or rear deck for styling and visibility.
Regulatory background
Most safety standards require a center high-mounted stop lamp to improve braking visibility for drivers behind. In the United States, the CHMSL requirement is part of FMVSS 108, while other regions have parallel regulations under their own vehicle safety standards. The light is intended to complement the two rear tail lights, providing an additional, higher‑mounted brake signal.
Placement and appearance can vary by vehicle, but the function remains the same: to clearly indicate when the vehicle is braking to reduce rear-end collisions.
Common configurations
Below are typical ways automakers mount and style the CHMSL. The list highlights the diversity in design while preserving the same safety purpose.
- Integrated into the rear window edge, often using LEDs for brightness and efficiency
- Mounted on the top edge of the trunk lid or rear hatch
- Attached to a rear spoiler or third‑generation light bar across the center
- Stacked or split with additional LEDs in sporty or luxury models
In all cases, the CHMSL serves as a high, conspicuous brake signal to drivers behind, regardless of the exact aesthetic integration.
Placement and appearance
Modern CHMSLs are designed to be highly visible even in bright daylight. They use LED technology in most new cars for quick response and longevity, and many vehicles position the lamp high enough to clear view obstructions from tailgaters.
Summary
Answer: The 3rd brake light is called the Center High Mount Stop Lamp (CHMSL), commonly referred to as the third brake light. It is the regulated, higher-mounted brake signal used alongside the standard rear lights and varies slightly in naming by region (e.g., CHMSL, Centre High Mounted Stop Lamp). Its primary purpose remains to improve braking visibility and safety for drivers behind.
What is another name for the third brake light?
CHMSL stands for the center high-mounted stop lamp. In a vehicle, the CHMSL is mounted above the left and right brake lights (also called stop lamps).
Do you legally need a 3rd brake light?
The federal government has required third brake lights on cars in the US since 1986 to improve the brake light's visibility.
What is your 3rd brake light?
Also known as center high mount stop lamps (CHMSL), 3rd brake lights provide an additional brake signal that's positioned for maximum visibility — helping alert drivers behind you sooner and reducing rear-end collisions.
What is the third brake light bulb called?
Center High Mount Stop Lamp
In North America, since 1986, all vehicles feature a third brake light. Legally, this is called the Center High Mount Stop Lamp, CHMSL for short, but informally called center brake lamp, high-level or eye-level brake lamp, cyclops brake light, or safety brake lamp.