Dodge Ram 3500 Back Up Light Bulb Size

Dodge Ram 3500 back up light bulb sizes include 921, 3057, and 3157 specifications for the replacement bulb. The replacement chart covers vehicle production years spanning 1994 to 2010.

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 3500 backup light specifications span model years 1994 through 2010, covering four distinct bulb types across that range: the 921, 3057, 3157, and 1156.
The 1156 bulb is the most frequently specified type in these records, covering the 1994-2000 and 1997-2000 model years continuously through 2001, making it the longest-running fitment in the dataset. It is a single-filament bulb with a BA15s bayonet base, rated at 12V and 21W.
The 921 is a T15 wedge-base bulb rated at 12V and 16W. It follows the ANSI standard applicable in both the US and Canada and was specified for the 2007-2010 model years.
The 3057 and 3157 are both T25 dual-filament wedge bulbs sharing identical voltage and wattage ratings of 12V with a 27W high-filament and 7W low-filament output. Despite these shared electrical characteristics, they are not the same part number and are not confirmed as interchangeable in these specifications.
The 3057 was specified for the 2003-2006 model years, while the 3157 was specified only for the 2002 model year. The physical and electrical similarity between these two types is a known source of fitment confusion in automotive applications.
The dual-filament design of the 3057 and 3157 bulbs, while present in these backup light positions, provides two separate circuits within a single bulb. In backup light applications, typically only one filament is active, though the socket must be wired to support the correct filament.
The 1156 uses a BA15s bayonet base, which is a single-contact bayonet mount. This base type is physically distinct from the wedge bases used by the 921, 3057, and 3157, meaning sockets designed for one base type are not compatible with the other.
All four bulb types in these specifications conform to ANSI standards recognized in both the US and Canada, indicating standardized sizing and electrical ratings across the listed fitments.
The transition from the 1156 bayonet-base bulb to the 3157 wedge bulb between the 2001 and 2002 Dodge Ram 3500 represents a change in both base type and filament count, which would require a different socket design in the vehicle.
The subsequent shift from the 3057 to the 921 between the 2006 and 2007 Dodge Ram 3500 marks a move from a dual-filament T25 wedge bulb to a single-filament T15 wedge bulb, reflecting a reduction in wattage from 27W to 16W in the backup light position.