Cadillac Allante Back Up Light Bulb Size

The Cadillac Allante back up light utilizes 1156 and P21W bulb sizes for the lighting system. Data for the specific components covers the period from 1987 through 1993.

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
1987-1993	1156

Bulb Specifications

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

Other Locations

Additional Notes

The Cadillac Allante uses the 1156 bulb for the back up light across all listed model years, spanning 1987-1993.
The 1156 is a single-filament bulb, meaning it serves one lighting function only, which is consistent with its dedicated back up light application.
The 1156 operates at 12 volts and 21 watts, placing it in the standard low-wattage range typical of automotive reverse lighting.
The 1156 uses a BA15s bayonet base, a single-contact mount where the "s" denotes a single pin, distinguishing it from the dual-contact BA15d variant.
The BA15s base design requires correct pin alignment during installation, as the single-contact configuration is not rotationally interchangeable with dual-contact bayonet sockets.
The 1156 carries ANSI standardization recognized in both the United States and Canada, indicating the bulb conforms to a defined set of dimensional and electrical tolerances.
Because the 1156 is a single-filament type, it is not interchangeable with visually similar dual-filament bulbs such as the 1157, which shares the same BA15 base family but uses a two-pin contact configuration.