International S2125 Back Up Light Bulb Size

The International S2125 back up light requires bulb size 1156 for proper installation and operation. Data for the specified lighting component covers the range from 1980 to 1981.

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
1980-1981	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 International S2125 backup light across both available model years, covering 1980-1981.
The 1156 operates on a 12-volt electrical system and draws 21 watts, placing it in the standard range for single-circuit automotive lighting applications.
As a single-filament bulb, the 1156 serves one dedicated function per socket, which aligns with its use in backup lights where only one lighting state is required.
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 base used in some other automotive bulbs.
The 1156 carries ANSI standardization recognized in both the United States and Canada, meaning the specification reflects a consistent electrical and physical standard across North American markets.
The BA15s base of the 1156 is not interchangeable with dual-contact bayonet bases. Substituting a visually similar bulb with a BA15d base would result in incorrect fitment for the International S2125.