Mercury Grand Marquis Map Light Bulb Size

The Mercury Grand Marquis map light utilizes bulb sizes 168, 105, 912, 1003, and 211-2 depending on the specific version of the vehicle. Available data covers the range from 1975 through 2011.

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
1992-2011	168
1990-1991	105
1989	912
1980-1988	105
1979	1003
1978	211-2
1975-1977	1003

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 4.9W.	168
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

Other Locations

Additional Notes

The Mercury Grand Marquis map light takes the 168 bulb across the 1992-2011 model years. This is a T10 miniature wedge bulb rated at 12V and 4.9W under the ANSI standard.
The wedge base of the 168 bulb allows it to seat directly into a socket without a separate metal base, which is a defining characteristic of the T10 form factor.
The 105 bulb is specified for the Mercury Grand Marquis map light across the 1980-1991 model years, with the exception of 1989. It is a single-filament bulb with a BA15s bayonet base, rated at 12V and 13W.
The 105 bulb is described as a variant of the 1156. While the two share the BA15s bayonet base, they differ in wattage, which makes them non-interchangeable in applications where thermal or electrical tolerances are strict.
The 1989 Grand Marquis map light uses the 912 bulb, a T15 wedge type rated at 12V and 12W. It is a variant of the 921 bulb, and the two are often cross-compatible due to their shared wedge base and close electrical ratings.
The 1003 bulb is specified for the 1975-1977 and 1979 model years. It shares the BA15s bayonet base with the 105 bulb but operates at a significantly higher wattage of 21W, making the two electrically incompatible as direct substitutes.
The 1978 Grand Marquis map light uses the 211-2, a festoon bulb with an SV8.5 base and a 41mm length, rated at 12V and 12W. Festoon bulbs are held in place by spring-loaded end caps rather than a socket, which is a distinct mounting method from the wedge and bayonet types used in other model years.
Across the full model range covered by these specifications, four different base types are represented: the T10 wedge, the T15 wedge, the BA15s bayonet, and the SV8.5 festoon base. None of these are interchangeable with one another at the socket level.
All bulbs listed in these specifications conform to ANSI standards applicable in both the United States and Canada, indicating consistent regulatory classification across the product range.
The wattage across the specified bulbs ranges from 4.9W for the 168 to 21W for the 1003, reflecting a substantial variation in power draw depending on the model year of the vehicle.