Ford Bronco II Back Up Light Bulb Size

The Ford Bronco II back up light utilizes 1156, P21W, and 3156 bulb sizes across various production versions. Data for the specific lighting components covers the period from 1984 through 1990.

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
1989-1990	3156
1984-1988	1156

Bulb Specifications

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

Other Locations

Additional Notes

The Ford Bronco II uses two distinct back up light bulb types across its production years: the 1156 for model years 1984-1988 and the 3156 for model years 1989-1990.
Both the 1156 and 3156 are ANSI-standardized bulbs recognized in the United States and Canada, meaning they conform to established dimensional and electrical specifications within those markets.
The 1156 is a single-filament bulb with a BA15s bayonet base, a base type characterized by a single pin offset to one side, which allows the bulb to seat in only one rotational position.
The 3156 is a single-filament wedge bulb in a T25 form factor, where the glass envelope itself acts as the retention mechanism rather than a separate metal base with pins.
Both bulb types operate at 12 volts, consistent with the standard electrical system voltage found in passenger vehicles and light trucks of this era.
The 1156 is rated at 21 watts, while the 3156 is rated at 27 watts, meaning the 1989-1990 Ford Bronco II back up lights draw more power than those on earlier model years.
Because the 1156 uses a bayonet base and the 3156 uses a wedge base, the two bulb types are not physically interchangeable despite sharing the same voltage rating.