Chevrolet S7 Back Up Light Bulb Size

The Chevrolet S7 back up light requires a bulb size of 1156 for the rear lighting system. Data for the specific bulb requirements covers the range from 1987 to 1988.

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
1987-1988	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 Chevrolet S7 backup light across both available model years, 1987-1988.
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 specifications shared across those markets.
It operates on a 12-volt system and draws 21 watts, which is typical of incandescent automotive backup lighting from that era.
The 1156 uses a BA15s bayonet base, a single-contact fitting where the "s" denotes a single pin, distinguishing it from the dual-pin BA15d variant used in other applications.
As a single-filament bulb, the 1156 serves one dedicated function per socket, unlike dual-filament types that can handle two lighting functions such as stop and tail simultaneously.
The BA15s base of the 1156 is not interchangeable with dual-contact bayonet bases, so substituting a physically similar but differently pinned bulb would result in an improper fit.