Center high-mount stop lamp (CHMSL) eye-level brake lamp, center brake lamp, and safety brake lamp-these are just some of the other names your third brake light goes by. This particular light has two main functions. Of course, there's the obvious function, which is to let approaching vehicles know that your ride is decelerating. Like your brake lights, this particular lamp is wired to brighten up each time you step on your brakes. But aside from serving as an add-on brake light, this lamp is also used in areas like North America to distinguish brake lights from red turn signals. This prevents confusion between other drivers when they spot your red lamps lighting up from afar. Now, like its many names, the third brake light may also have varying locations based on the vehicle's design. Common locations include above and inside the vehicle's rear window, on a vehicle's spoiler, on the deck lid, and on the spare tire wheel carrier. On larger vehicles like commercial vans and trucks, this brake light may also be found on the edge of the vehicle's roof. The main reason behind its varying locations is that third brake lights need to be installed on the most noticeable parts of a ride's rear end. This enables the third brake light to carry out its purpose properly. Though third brake lights are designed for years of service, impact and a worn bulb can render this light assembly useless. When this happens, replace your third brake lamp immediately.