The Mercedes-Benz 350SDL brake light requires a unique P21W bulb size for proper installation and function. Data for the specific bulb requirements covers the range from 1990 to 1991.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The P21W is the sole bulb type listed across all brake light positions for the Mercedes-Benz 350SDL, covering both the standard brake lights and the center high mount stop light for 1990-1991.
The P21W follows the ECE (Economic Commission for Europe) standard, a regulatory framework used across Europe and numerous other markets worldwide to govern automotive lighting performance and construction.
The P21W operates at 12 volts with a 21-watt output, which is the conventional rating for single-filament signalling applications in passenger vehicles.
As a single-filament bulb, the P21W is dedicated to one switching function only, making it distinct from dual-filament types that serve combined roles such as tail and brake lighting simultaneously.
The P21W uses a BA15s bayonet base, where "BA" denotes a bayonet cap fitting, "15" refers to the 15mm base width, and the lowercase "s" indicates a single contact at the base.
The BA15s base is not interchangeable with the BA15d base, which carries two contacts and is used on dual-filament bulbs. Substituting one for the other is not possible due to the differing contact configurations.
The same P21W specification applies to both the standard brake light and the center high mount stop light positions on the 350SDL for 1990-1991, indicating a uniform bulb fitment across all three stop light locations.