Bricklin SV-1 Back Up Light Bulb Size

The Bricklin SV-1 back up light requires bulb size 1156 or P21W depending on the specific production requirements for the vehicle. Data for the lighting components covers the range from 1974 to 1976.

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
1974-1976	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 1156 is the sole bulb type listed for the Bricklin SV-1 backup light across the 1974-1976 model years.
The 1156 is an ANSI-standardized bulb recognized in both the United States and Canada, meaning it conforms to a defined set of electrical and physical tolerances shared across manufacturers.
It operates on a 12-volt circuit and draws 21 watts, which is typical of incandescent backup lighting from that era.
The 1156 uses a BA15s bayonet base, a single-contact fitting where the "s" denotes a single pin rather than the dual-pin arrangement found on related bayonet types such as the BA15d.
As a single-filament bulb, the 1156 serves one dedicated function per socket, distinguishing it from dual-filament types like the 1157, which handle two functions such as braking and running light simultaneously.
The BA15s base is not interchangeable with dual-contact bayonet bases, so substituting a dual-filament bulb in a single-contact socket is not a compatible replacement for the SV-1 backup light position.