Dodge Ram 2500 Back Up Light Bulb Size

The Dodge Ram 2500 back up light utilizes 921, 3057, 3157, P21W, and 1156 bulb sizes depending on the specific production version. Available data covers a range from 1994 through 2010 for the specified vehicle 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
2007-2010	921
2003-2006	3057
2002	3157
1994-2001	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3057
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 Dodge Ram 2500 backup light specifications span model years 1994 through 2010 and reference four distinct bulb types: 921, 3057, 3157, and 1156.
The 1156 bulb is the most frequently specified type across this range, covering the Dodge Ram 2500 from 1994 through 2000 and again in 2001, accounting for eight model years in total.
The 1156 is a single-filament bulb with a BA15s bayonet base, operating at 12V and 21W. The bayonet base uses a twist-and-lock mounting style, which differs from the wedge-style base found on the other bulbs in these specifications.
The 921 bulb is a T15 wedge type rated at 12V and 16W. It is specified for the 2007-2010 model years and carries a single filament, making it suited only for a single-function application such as a backup light.
The 3057 and 3157 are both dual-filament T25 wedge bulbs rated at 12V with a 27W high filament and a 7W low filament. Despite their shared wattage ratings and physical T25 wedge form, they are not universally interchangeable, as internal filament positioning differs between the two types.
The 3057 is specified for the 2003-2006 model years, while the 3157 is specified exclusively for 2002. Substituting one for the other without confirming socket compatibility risks improper fitment or electrical function.
All four bulb types conform to ANSI standards recognized in both the United States and Canada, indicating standardized electrical and physical tolerances across the range.
The transition from the 1156 bayonet-base bulb to wedge-style bulbs beginning with the 2002 model year reflects a change in socket design, meaning bulbs from earlier model years are not physically compatible with sockets from later ones.
The 921 operates at a lower wattage than the 1156, 3057, and 3157. At 16W, it produces less light output than the 21W 1156 or the 27W high filament of the 3057 and 3157 under equivalent conditions.
Because the 3057 and 3157 carry dual filaments, their use in a single-function backup light circuit means only one filament is active during operation, with the second filament remaining unused in that application.