Subaru GL Back Up Light Bulb Size

The Subaru GL back up light utilizes 1156 and P21W bulb sizes for the rear illumination system. Data for the specific components covers the range from 1980 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
1980-1989	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 uses the 1156 bulb for the back up light across the 1980-1989 model years.
The 1156 is an ANSI-standardized bulb type recognized in both the United States and Canada.
It is a single-filament bulb, meaning it serves one lighting function rather than switching between two brightness levels.
The 1156 uses a BA15s bayonet base, which features a single locating pin on the side of the base for mounting and alignment.
The bulb operates at 12 volts, consistent with standard automotive electrical systems.
At 21 watts, the 1156 falls within the mid-range of common automotive bulb wattages for single-filament applications.
The BA15s base designation is single-contact, and substituting a dual-contact bayonet base bulb such as the 1157 would result in an incompatible fit despite a similar physical appearance.