Saturn SC1 Back Up Light Bulb Size

The Saturn SC1 back up light utilizes 921, P21W, and 1156 bulb sizes depending on the specific version of the component. Data for the provided specifications covers the period from 1993 through 2002.

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
2001-2002	921
1993-2000	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

Other Locations

Additional Notes

The Saturn SC1 back up light specifications cover model years 1993-2002.
Two bulb types appear across these model years: the 921 and the 1156, both conforming to ANSI standards recognized in the US and Canada.
The 1156 is a single-filament bulb with a BA15s bayonet base, rated at 12V and 21W. The BA15s designation indicates a single-contact bayonet fitting, which locks into its socket with a twist.
The 921 is a T15 wedge bulb, rated at 12V and 16W. A wedge base uses no separate metal base; the glass envelope itself holds the bulb in place within the socket.
The 1156 draws 21W while the 921 draws 16W, meaning the two bulb types are not electrically equivalent despite both operating on a 12V system.
The Saturn SC1 (1993-2000) uses the 1156 bulb for the back up light across eight consecutive model years.
The Saturn SC1 (2001-2002) uses the 921 bulb, which represents a change in both base type and wattage relative to earlier model years.
Because the 921 uses a wedge base and the 1156 uses a BA15s bayonet base, the two bulbs are physically incompatible with each other's sockets and are not interchangeable.