Third Brake Light
The Third Brake Light, also known as the Center High-Mounted Stop Lamp (CHMSL), is an additional brake light located higher than the standard rear brake lights, typically in the rear window, on the roof, or on the rear deck. Its primary function is to provide a distinct visual cue for braking, reducing rear-end collision risks by distinguishing brake application from tail lights.
Function & Safety
- Collision Reduction: Studies indicate CHMSLs reduce rear-end collisions by 1–5% by providing a unique signal location.
- Visibility: Positioned to be visible even when the rear bumper is obscured by cargo or other vehicles.
- Regulation: Mandated in many jurisdictions (e.g., US FMVSS 108, EU ECE R48) for new vehicles since the late 1980s/early 1990s.
Technical Implementation
- Technology: Traditionally incandescent bulbs; modern implementations use LED arrays for faster response times and lower power consumption.
- Integration: Often integrated into the rear windshield, spoiler, or trunk lid.
- Custom Modifications: Enthusiasts sometimes integrate custom lighting solutions into classic cars lacking factory CHMSLs.
Notable Integrations
- 1970 Lincoln Continental Mark III Hidden RGB LED Third Brake Light Integration: A detailed case study of integrating a hidden RGB LED third brake light into a vintage 1970 Lincoln Continental Mark III, demonstrating modern retrofit techniques for classic vehicles.