Chevrolet R/V Series Back Up Light Bulb Size

Chevrolet R/V Series back up light bulbs utilize 3156, 2456, and 1156 bulb sizes depending on specific model configurations. The replacement chart covers 1987 through 1991 production years with corresponding bulb size specifications.

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
1991	3156
1990	2456
1987-1989	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament wedge bulb (T25). 12V, 27W.	3156
ANSI standard (US & Canada). Festoon bulb, specialty application. 12V.	2456
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

Other Locations

Additional Notes

The Chevrolet R/V Series back up light specifications cover model years 1987 through 1991, with three distinct bulb types used across that span.
The 1156 bulb is the most frequently specified type, covering the 1987-1989 model years. It is a single-filament bulb with a BA15s bayonet base, rated at 12V and 21W, and meets ANSI standards for the US and Canada.
The BA15s bayonet base on the 1156 is a single-contact fitting, meaning it is not interchangeable with dual-contact bayonet bases found on other bulb types.
The 1990 model year uses the 2456, a festoon-style bulb rated at 12V and conforming to ANSI standards for the US and Canada. Festoon bulbs are cylindrical in form and mount by contact pressure at each end rather than by a base socket.
The 1991 model year uses the 3156, a single-filament wedge bulb of the T25 type, rated at 12V and 27W, also meeting ANSI standards for the US and Canada.
The T25 designation on the 3156 refers to its wedge base size, which is not compatible with the BA15s bayonet socket used by the 1156, making the 1991 specification physically distinct from the 1987-1989 fitment.
The wattage difference between the 1156 (21W) and the 3156 (27W) indicates a higher power output for the 1991 specification, which affects the brightness of the back up light on that model year.
The 2456 festoon type used in 1990 represents a departure from both the bayonet and wedge base formats used in adjacent model years, indicating a housing design change for that year on the Chevrolet R/V Series.
All three bulb types operate on a 12V electrical system, consistent with standard automotive voltage across the full 1987-1991 range.
Because the 1987-1989, 1990, and 1991 model years each use a different base type, bulbs from one group are not directly interchangeable with those from another without a corresponding socket change.