Subaru GL-10 Back Up Light Bulb Size

The Subaru GL-10 back up light utilizes bulb sizes 1156 and P21W according to the provided technical specifications. Data for the specified lighting components covers the period from 1985 through 1989.

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
1985-1989	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 Subaru GL-10 uses the 1156 bulb for the back up light across all listed model years, spanning 1985-1989.
The 1156 is a single-filament bulb, meaning it serves one lighting function only, which in this application is the back up light.
The 1156 operates at 12 volts and 21 watts, consistent with standard automotive electrical systems.
The 1156 uses a BA15s bayonet base, a single-contact bayonet mount with a 15mm base width, which requires a matching socket for proper fitment.
The 1156 carries ANSI standardization, indicating its specifications are recognized across the United States and Canada.
Because the BA15s base is a single-contact design, it is not interchangeable with the BA15d double-contact bayonet base used on dual-filament bulbs such as the 1157.