Ford Mustang Back Up Light Bulb Size

The Ford Mustang back up light utilizes 1142, 1156, 2356, 2456, 2458, 3156, 3157, and P21W bulb sizes. Available data for the specified components covers the range from 1964 to 2023.

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
2021-2023	3156
2015-2020	3157
2002	2356
1997-1998	2456
1996	3156
1994-1995	2456
1992-1993	2356
1991	3156
1990	2356
1989	2456
1988	3156
1987	1156
1979-1983	1156
1971-1973	1156
1964-1970	1142

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament wedge bulb (T25). 12V, 27W.	3156
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3157
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V.	2356
ANSI standard (US & Canada). Festoon bulb, specialty application. 12V.	2456
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W.	1142

Other Locations

Additional Notes

The Ford Mustang backup light specifications cover model years 1964 through 2023, with six distinct bulb types represented across that span: the 1142, 1156, 2356, 2456, 3156, and 3157.
The 3156 and 3157 are both T25 wedge bulbs operating at 12V, and they share the same physical housing form. The key difference is that the 3156 is a single-filament bulb rated at 27W, while the 3157 carries a dual filament rated at 27W and 7W. This distinction makes them non-interchangeable despite their similar appearance.
The Ford Mustang (2021-2023) uses the 3156, a single-filament T25 wedge bulb, for the backup light position.
The 3157 dual-filament wedge bulb is specified for the 2015-2020 Mustang backup light position. Installing a 3156 in place of a 3157 would result in only one filament circuit being served, which may affect intended lighting behavior if the socket is wired for dual-filament use.
The 1142 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V with filaments at 21W and 5W. It is noted as a variant of the 1157 type. The 1964-1970 Mustang uses this bulb for the backup light.
The 1156 is a single-filament bulb with a BA15s bayonet base, rated at 12V and 21W. It is specified for the 1971-1973 and 1979-1983 Mustang, as well as the 1987 model year.
The BAY15d base used by the 1142 and 2356 bulbs features two offset pins, which physically prevents installation into a BA15s socket used by the 1156. These base types are not interchangeable.
The 2456 is classified as a festoon-style specialty bulb with a 12V rating. It is specified for the 1989, 1994-1995, and 1997-1998 Mustang backup light positions.
The 2356 uses a BAY15d bayonet base and is a dual-filament bulb rated at 12V. It appears in the 1990, 1992-1993, and 2002 Mustang backup light specifications.
The 3156 also appears in earlier model years, specifically the 1988, 1991, and 1996 Mustang, in addition to its use in the 2021-2023 range, indicating the same T25 wedge single-filament specification was applied across non-consecutive generations.