Ford Bronco Back Up Light Bulb Size

The Ford Bronco back up light utilizes bulb sizes WT21W, 2456, 2356, P21W, 1156, and 199. Available information covers the range of 1972 through 2023 for the specified components.

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	WT21W
1996	2456
1995	2356
1992-1994	2456
1979-1991	1156
1978	199
1977	1156
1976	199
1974-1975	1156
1973	199
1972	1156

Bulb Specifications

Description	Bulb Size
Ford OEM part. Single-filament wedge bulb (T20). Originally used in 2021+ Ford F-150, Bronco, and Maverick. 12V, 21W.	WT21W
ANSI standard (US & Canada). Festoon bulb, specialty application. 12V.	2456
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V.	2356
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 21W.	199

Other Locations

Additional Notes

The Ford Bronco (2021-2023) uses the WT21W bulb for the back up light, a Ford OEM single-filament wedge bulb in the T20 form factor, rated at 12V and 21W.
The WT21W is a wedge-base bulb, meaning it lacks a metal base pin and instead relies on wire leads pressed into a socket, which is a different retention mechanism than the bayonet-style bulbs used in earlier Bronco model years.
The 1156 is the most frequently specified bulb across the Bronco back up light data, covering the 1972, 1974-1975, 1977, and 1979-1991 model years.
The 1156 is a single-filament bulb with a BA15s bayonet base, rated at 12V and 21W, and follows the ANSI standard applicable in both the US and Canada.
The bulb size 199 is specified for the Ford Bronco in 1973, 1976, and 1978. It shares the BA15s bayonet base and the 12V, 21W rating with the 1156, and is classified as a variant of that bulb type.
Because the 199 and 1156 share the same base type and wattage, the physical and electrical similarities between them are notable, though fitment decisions should be based on the year-specific specification rather than assumed interchangeability.
The 2456 is specified for the Ford Bronco in 1992-1994 and 1996. It is a festoon-style bulb, which uses two end caps rather than a base pin or bayonet fitting, and is rated at 12V under the ANSI standard.
The 1995 Ford Bronco is the only model year in the specifications to use the 2356 bulb. The 2356 is a dual-filament bulb with a BAY15d bayonet base, which is an offset-pin variant that prevents incorrect single-filament bulbs from being seated in its place.
The BAY15d base of the 2356 is physically distinct from the BA15s base of the 1156 and 199 bulbs. The offset pin arrangement of the BAY15d is a deliberate design feature to prevent cross-installation with single-filament bulbs.
The back up light bulb type for the Ford Bronco changed across several distinct eras: festoon-style (2456) in most of the early-to-mid 1990s, bayonet-base single-filament (1156 and 199) across the majority of earlier decades, and wedge-base (WT21W) in the 2021-2023 generation.