The Mercedes-Benz 500SL brake light uses 1156 and P21W bulb sizes according to the provided data. Information for the specified vehicle covers the period from 1990 through 1993.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercedes-Benz 500SL uses the 1156 bulb for the brake lights across the 1990-1993 model years.
The 1156 is an ANSI-standardized single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, which is a single-contact base with a 15mm collar.
Single-filament construction in the 1156 means the bulb serves one dedicated function, as opposed to dual-filament types that handle two lighting functions from a single housing.
The Center High Mount Stop Light on the 500SL uses the 12961 bulb across the same 1990-1993 model years.
The 12961 is a Philips part number designating a miniature T10 wedge bulb rated at 12V and 5W, fitted with a W2.1x9.5d wedge base.
The W2.1x9.5d base is a pinch-style wedge fitting held in place by socket tension rather than a twist or bayonet lock, which is a common format for low-wattage indicator and auxiliary lighting positions.
The 1156 and 12961 use entirely different base types, a bayonet and a wedge respectively, making them physically non-interchangeable despite both operating on a 12V system.
The wattage difference between the two bulbs is significant: the 1156 draws 21W while the 12961 draws 5W, reflecting their respective roles as a primary brake signal source and a supplemental high-mount stop light.