The CHMSL (Center High Mount Stop Lamp) is the center-high mounted third brake light at the rear of a vehicle. This auxiliary brake light is intended to improve visibility and road safety , especially for drivers following behind.
1. Characteristics of a CHMSL
✅ Placed in the center, higher than the standard brake lights → Usually above the rear window or on the trunk.
✅ Red light → Just like regular brake lights, but more visible due to the higher position.
✅ Turns on when the brake is pressed → Functions the same as the other brake lights.
✅ Mandatory on modern vehicles → Legally required on cars in many countries since the 1980s and 1990s.
✅ Can be halogen, LED or neon → Modern versions often use LED technology for faster activation and longer life.
2. Benefits of a CHMSL
🚗 Increases road safety → Makes braking actions more visible, especially for drivers further down the lane.
👀 Reduces risk of rear-end collisions → Studies show that CHMSLs reduce accidents by up to 50% in heavy traffic.
💡 Better visibility in stop-and-go traffic → Especially useful when a vehicle's standard brake lights are blocked by other vehicles.
🔧 Long lifespan with LED versions → Modern CHMSLs have a longer lifespan and consume less energy.
3. Types of CHMSLs
| Type CHMSL | Light source | Features |
|---|---|---|
| Halogen CHMSL | Light bulb | Cheap, but outdated and less efficient. |
| LED CHMSL | LED | Fast activation, energy efficient, long life. |
| Neon CHMSL | Neon tube | Rare, but was used in some older luxury cars. |
| Dynamic CHMSL | LED (flashing or animated) | Models with flashing or pulse function for extra visibility. |
📌 Modern cars almost always have LED CHMSLs due to their higher efficiency and reliability.
4. Legislation and obligation
📌 Mandatory in many countries since the 1980s and 1990s for passenger cars.
📌 Mandatory in the EU on all M1 category vehicles (passenger cars) since 1998 .
📌 Required on passenger cars in the US since 1986 and on light trucks since 1994 .
📌 Some countries allow flashing CHMSLs during hard braking (such as in certain Asian and European markets).
💡 In short:
The CHMSL (Center High Mount Stop Lamp) is an additional, higher-mounted brake light that helps improve visibility and prevent rear-end collisions . It is mandatory in many countries , is usually LED , and is an essential component of modern vehicle safety systems .