Lincoln Mark VII Back Up Light Bulb Size

The Lincoln Mark VII back up light utilizes 1156, 2356, 2456, 3156, and P21W bulb sizes for the rear illumination system. Available data for the specific lighting components covers the period from 1984 through 1992.

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	2356
1991	3156
1990	2456
1989	3156
1984-1988	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V.	2356
ANSI standard (US & Canada). Single-filament wedge bulb (T25). 12V, 27W.	3156
ANSI standard (US & Canada). Festoon bulb, specialty application. 12V.	2456
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

Other Locations

Additional Notes

The Lincoln Mark VII backup light specifications cover model years 1984-1992 and reference four distinct bulb types across that span: 1156, 2356, 2456, and 3156.
The 1156 bulb is the most frequently specified type for the Lincoln Mark VII backup light, appearing across five consecutive model years from 1984-1988. It is a single-filament bulb rated at 12V and 21W, mounted with a BA15s bayonet base.
The BA15s bayonet base on the 1156 uses a single contact pin, which is not interchangeable with the BAY15d base found on the 2356 bulb, as the latter uses offset dual contact pins to prevent incorrect installation.
The 3156 is a single-filament wedge-type bulb in a T25 form factor, rated at 12V and 27W. It does not use a bayonet base, which makes it physically incompatible with sockets designed for the 1156 or 2356.
The 1991 and 1989 model years both specify the 3156, while the years surrounding them call for different bulb types, indicating the backup light socket configuration was not consistent across the production run.
The 2356 specified for the 1992 model year is a dual-filament bulb with a BAY15d bayonet base, operating at 12V. Its dual-filament design distinguishes it from all other bulb types listed in these specifications, which are single-filament.
The 2456 specified for the 1990 model year is classified as a festoon bulb intended for specialty applications, operating at 12V. A festoon bulb seats by spring tension between two end caps rather than using a bayonet or wedge mount, making it incompatible with sockets designed for any of the other three bulb types in these specifications.
All four bulb types listed carry ANSI standard designations recognized in both the United States and Canada, meaning the numerical codes correspond to standardized electrical and physical specifications rather than proprietary designations.
Because the backup light bulb type changes across multiple model years, the specific year of the vehicle is a necessary reference point before selecting a replacement, as bulbs sharing a 12V rating are not interchangeable across different base and socket types.