Center High Mount Stop Light

What Is a Center High Mount Stop Light?

The Center High Mount Stop Light (CHMSL) — commonly called the "third brake light" — is one of the most important rear safety lighting components on any vehicle. Unofficially known as the "third brake light," the CHMSL is typically positioned at a high point on a vehicle's rear end, enabling a following vehicle to better see that a vehicle ahead is applying its brakes. Its elevated position is by design: the CHMSL is intended to provide a warning to drivers whose view of the vehicle's left and right stop lamps is blocked by interceding vehicles.

Why the CHMSL Matters for Safety

Center High Mounted Stop Lamps have been standard equipment on all new passenger cars sold in the United States since model year 1986 and all new light trucks since model year 1994, as required by Federal Motor Vehicle Safety Standard 108. The safety case for this component is well established: over the long term, the technology has helped reduce rear crashes by about 4.3 percent annually, according to the National Highway Traffic Safety Administration (NHTSA).

The CHMSL also provides a redundant stop light signal in the event of a stop lamp malfunction. In North America, where rear turn signals are permitted to emit red light, the CHMSL also helps to disambiguate brake lights from rear position lights and turn signal lights. These overlapping safety functions make the CHMSL far more than just a regulatory checkbox — it is an active line of defense against rear-end collisions.

When Should You Replace Your CHMSL?

A burned-out or damaged CHMSL not only removes a critical layer of protection from following traffic, but it can also result in a traffic citation, since federal law mandates it as required equipment. Common replacement triggers include a blown bulb, a cracked or yellowed lens that reduces light output, a faulty wiring connector, or physical damage from a minor collision. When the CHMSL is mounted at the top of the cab of a pickup truck, cargo that is loaded in or above the bed may obstruct the CHMSL, and similarly, a cap or camper that is installed in the bed may also obstruct it — making aftermarket relocation or auxiliary CHMSL units a popular choice for truck owners who haul frequently.

Key Considerations When Shopping for a Center High Mount Stop Light

• OEM vs. Aftermarket: OEM-style replacements offer direct plug-and-play fitment, while aftermarket units can add upgraded LED technology or a custom look.
• Bulb Type: A CHMSL may use one or more filament bulbs or LEDs, or a strip of neon tube as its light source. LED units typically offer faster illumination response times and longer service life than incandescent alternatives.
• Vehicle-Specific Fitment: Always verify that the CHMSL you choose is designed for your specific year, make, and model to ensure proper mounting and wiring compatibility.
• Lens Clarity & Housing Quality: UV-resistant lenses and weatherproof housings extend the unit's lifespan, especially for trucks and SUVs exposed to the elements.

Top Brands for Center High Mount Stop Lights

Body Armor is well known in the off-road and truck accessory market, and their CHMSL solutions are built with rugged, trail-ready durability in mind — an excellent choice for 4x4 enthusiasts who modify their truck beds or add toppers that require relocated brake lighting.

Anzo USA is a leading name in aftermarket automotive lighting, recognized for bringing modern LED technology and aggressive styling to replacement lighting components. Their CHMSL offerings combine bright, efficient illumination with a refined appearance that complements both stock and custom builds.