Dodge B150 Back Up Light Bulb Size

The Dodge B150 back up light utilizes bulb sizes 921, 1156, and P21W depending on the specific version of the component. Available data for the bulb sizes covers the range from 1981 to 1994.

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
1994	921
1981-1993	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

Other Locations

Additional Notes

The 1156 bulb is the back up light specification for the Dodge B150 across the 1981-1993 model years.
The 1156 is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base, and meets ANSI standards for the US and Canada markets.
A BA15s bayonet base uses a single contact pin, which means it is not interchangeable with dual-contact bayonet bases such as the BA15d found on double-filament bulbs.
For the 1994 model year, the Dodge B150 back up light specification changes to the 921 bulb, which is a T15 wedge-type rather than a bayonet-base type.
The 921 wedge bulb is rated at 12V and 16W, making it 5 watts lower in output than the 1156 used in prior model years.
Because the 921 uses a wedge base and the 1156 uses a BA15s bayonet base, the two bulb types are physically incompatible and cannot be substituted for one another without a socket adapter or housing modification.
Both the 921 and the 1156 conform to ANSI standards applicable in the US and Canada, indicating standardized electrical and physical tolerances for each respective type.
The T15 designation of the 921 refers to the tubular glass envelope size, where the number 15 represents a width of 15 eighths of an inch.