Mercury Marquis Map Light Bulb Size

The Mercury Marquis map light utilizes bulb sizes 105, 912, 1003, 211-2, 212-2, 1816, and 631 depending on the specific vehicle configuration and internal lighting requirements. Available data for the specified lighting components covers a range from 1967 through 1986 for the various bulb applications listed.

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
1985-1986	105
1984	912
1980-1983	105
1978-1979	1003
1977	211-2
1974-1976	1003
1972-1973	212-2
1968-1971	1816
1967	631

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 13W.	105
ANSI standard (US & Canada). Wedge bulb (T15). Variant of 921. 12V, 12W.	912
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1003
ANSI standard (US & Canada). Festoon bulb, 41mm length, SV8.5 base. 12V, 12W.	211-2
ANSI standard (US & Canada). Festoon bulb, 41mm length, SV8.5 base. 12V, 12W.	212-2
ANSI standard (US & Canada). Miniature wedge bulb (T3.25). 12V, 4W.	1816
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 21W.	631

Other Locations

Additional Notes

The bulb size 105 is the most frequently specified map light bulb across the Mercury Marquis model range, covering the 1980-1986 model years with the exception of 1984.
The 105 is a single-filament bulb with a BA15s bayonet base, rated at 12V and 13W, and is classified as a variant of the 1156 under the ANSI standard used in the US and Canada.
The 1003 bulb also uses a BA15s bayonet base and shares the same single-filament construction as the 105, but draws more power at 21W versus 13W, making the two bulbs electrically incompatible despite their physical base similarity.
The 1003 was the specified map light bulb for the Mercury Marquis across the 1974-1976 and 1978-1979 model years.
The 631 bulb, specified for the 1967 Mercury Marquis, is also a single-filament BA15s bayonet-base bulb rated at 12V and 21W, placing it in the same wattage class as the 1003 and likewise classified as a variant of the 1156.
The 1816 is a miniature wedge bulb of the T3.25 type rated at only 4W, making it the lowest-wattage bulb in these specifications, and it was used across the 1968-1971 model years.
The 211-2 and 212-2 are both festoon bulbs with a 41mm length and SV8.5 base, each rated at 12V and 12W under the ANSI standard, and they share identical electrical and physical characteristics.
The 211-2 was specified for the 1977 model year, while the 212-2 covered the 1972-1973 model years, meaning these two interchangeable festoon bulbs spanned three model years in total.
The 912 wedge bulb of the T15 type, rated at 12V and 12W and classified as a variant of the 921, was specified solely for the 1984 Mercury Marquis, making it the only wedge-type bulb among the map light specifications for this model.
Because the BA15s bayonet base is shared among the 105, 1003, and 631 bulbs, physical fitment alone does not confirm electrical interchangeability, as their wattage ratings differ across those three types.