Lincoln LS Back Up Light Bulb Size

Lincoln LS back up light bulbs utilize 921 and 3157 bulb sizes for replacement applications. The replacement chart covers vehicle production spanning 2000 to 2006.

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
2003-2006	921
2000-2002	3157

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3157

Other Locations

Additional Notes

The Lincoln LS backup light uses two distinct bulb sizes across its production run, with the 921 fitted to 2003-2006 models and the 3157 fitted to 2000-2002 models.
The 921 is a single-filament wedge bulb rated at 12V and 16W, conforming to the T15 form factor under the ANSI standard recognized in both the US and Canada.
The 3157 is a dual-filament wedge bulb rated at 12V with a 27W main filament and a 7W secondary filament, conforming to the T25 form factor under the same ANSI standard.
Because the 921 and 3157 are both wedge-type bulbs, they share a similar base style, but their wattage ratings and filament configurations differ significantly, making them non-interchangeable for the Lincoln LS backup light application.
The dual-filament design of the 3157 is a notable distinction from the single-filament 921; installing a dual-filament bulb in a socket wired for a single-filament application, or vice versa, risks incorrect circuit behavior or fitment failure.
The T15 and T25 designations refer to the tubular envelope size of each bulb, with T25 being physically larger than T15, which further reinforces that the two bulb types are not interchangeable despite sharing a wedge base style.
The 11W difference in primary wattage between the 921 (16W) and the 3157 (27W) means the 3157 produces noticeably more light output, a factor relevant when sourcing a replacement for the correct model year.