Ford F-650 Back Up Light Bulb Size

The Ford F-650 back up light uses 3157, P21W, and 1156 bulb sizes depending on the specific vehicle configuration. Available data covers the range from 2000 through 2022.

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
2021-2022	3157
2017-2019	3157
2000-2003	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3157
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

Other Locations

Additional Notes

The Ford F-650 backup light specifications cover model years 2000-2003 and 2017-2022, with two distinct bulb types used across these periods.
The 3157 is the more frequently listed bulb in these specifications, appearing across five model years: 2017-2019 and 2021-2022.
The 3157 is a dual-filament T25 wedge bulb rated at 12V with a 27W primary filament and a 7W secondary filament, conforming to ANSI standards recognized in both the US and Canada.
The dual-filament design of the 3157 means the bulb carries two separate circuits within a single housing, which is a characteristic not shared by all backup light bulbs.
The 1156 is specified for the Ford F-650 across model years 2000-2003, representing four of the nine total entries in these specifications.
The 1156 is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, and also conforms to ANSI standards for the US and Canadian markets.
The BA15s bayonet base of the 1156 and the wedge base of the 3157 are physically incompatible mounting types, meaning the two bulbs are not interchangeable without a socket adapter or wiring modification.
The wattage difference between the two bulbs is notable: the 1156 operates at a single 21W output, while the 3157 draws 27W on its primary filament, reflecting a higher light output in the later specification.
Both bulb types operate on a 12V electrical system, which is standard for automotive applications in this vehicle class.
The shift from the 1156 to the 3157 between the 2003 and 2017 model years represents a change in both base type and filament configuration for the F-650 backup light position.