Cadillac Seville Back Up Light Bulb Size

The Cadillac Seville back up light utilizes unique bulb sizes including 2458, 3157, 1156, P21W, 2057, and 3057 depending on the specific production version. Available data for the specified lighting components covers the range from 1976 through 2004.

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
2000-2004	3157
1993-1999	1156
1992	2057
1990-1991	3057
1976-1989	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
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Brighter variant of 1157. 12V, 26.9W/8W.	2057
ANSI standard (US & Canada). Dual-filament wedge bulb (T25). 12V, 27W/7W.	3057

Other Locations

Additional Notes

The Cadillac Seville back up light specifications cover model years 1976 through 2004 and reference four distinct bulb types: 3157, 1156, 2057, and 3057.
The 1156 is a single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base. Because it carries only one filament, it serves a single lighting function rather than a combined stop/tail or similar dual-purpose role.
The Cadillac Seville uses the 1156 across the widest span of model years in these specifications, covering 1976-1984, 1987-1999, with the 1985-1986 years also included in that same bulb designation.
The 3157 is a dual-filament wedge bulb of the T25 type, rated at 12V with a 27W high filament and a 7W low filament. The Cadillac Seville uses this bulb for the back up light across the 2000-2004 model years.
The 3057 is also a dual-filament T25 wedge bulb sharing the same 12V, 27W/7W rating as the 3157. It appears in the 1990-1991 model years. Despite identical wattage ratings, the 3057 and 3157 are not confirmed as interchangeable within these specifications.
The 2057 is a dual-filament bulb with a BAY15d bayonet base, rated at 12V, 26.9W/8W, and is described as a brighter variant of the 1157. It is specified solely for the 1992 model year.
The base type is a critical fitment factor. The 1156 uses a BA15s single-contact bayonet base, while the 2057 uses a BAY15d dual-contact bayonet base. These two base types are physically distinct and not interchangeable despite their similar bayonet-style mounting.
The 3157 and 3057 are both T25 wedge-base bulbs, meaning they share the same physical connector format. However, their ANSI designations differ, and substitution between them is not supported by these specifications.
A bulb type change occurs at the 1999-2000 model year boundary, where the specification shifts from the single-filament 1156 to the dual-filament 3157. This represents a change in both filament count and base type for the back up light position.
All four bulb types listed are ANSI-standardized for the US and Canadian markets and operate on a 12V electrical system, consistent with standard automotive electrical architecture.