Mercedes-Benz 280SE Map Light Bulb Size

The Mercedes-Benz 280SE map light requires bulb size 3893 or 12821 depending on the specific application. Data for the bulb sizes covers the range from 1968 to 1980.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1977-1980	3893
1968-1973	12821

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base, specialty application. 12V.	3893
Philips part number. Miniature wedge bulb (T10) with W2.1x9.5d base. 12V, 5W.	12821

Other Locations

Additional Notes

The Mercedes-Benz 280SE map light specifications cover model years 1968-1980, split across two distinct bulb types depending on the production era.
The 12821 bulb is a Philips part number designating a miniature wedge-type bulb in the T10 form factor, fitted with a W2.1x9.5d base and rated at 12V and 5W.
The T10 wedge base design of the 12821 relies on friction retention rather than a locking mechanism, meaning the bulb is held in place by the socket walls alone.
The 12821 bulb applies to the 1968-1973 model years of the Mercedes-Benz 280SE map light position.
The 3893 is an ANSI-standard bulb recognized in the United States and Canada, operating at 12V with a BAY15d bayonet base and a dual-filament configuration.
A BAY15d bayonet base features two offset pins at different heights, a physical design that prevents incorrect single-filament bulbs from being seated in its place.
The dual-filament nature of the 3893 classifies it as a specialty application bulb, distinguishing it from the single-filament 12821 used in earlier model years.
The 3893 bulb applies to the 1977-1980 model years of the map light position.
The two bulb types are not interchangeable. The BAY15d bayonet base of the 3893 and the W2.1x9.5d wedge base of the 12821 are physically incompatible socket types.
The base type difference also reflects a functional distinction, as the 3893 carries two filaments while the 12821 carries one, making substitution between the two unsuitable regardless of voltage compatibility.