Subaru DL Back Up Light Bulb Size

The Subaru DL back up light utilizes 1156, P21W, and 1157 bulb sizes for the rear illumination system. Data for the specific components covers the range from 1976 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
1976-1979	1157

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. 12V, 21W/5W.	1157

Other Locations

Additional Notes

The Subaru DL uses the 1156 bulb for the back up light across the 1980-1989 model years.
The 1156 is an ANSI-standard single-filament bulb rated at 12V and 21W, fitted with a BA15s bayonet base.
The BA15s base designation indicates a single-contact bayonet mount, which is not interchangeable with dual-contact bayonet bases.
The 1976-1979 Subaru DL back up light specification calls for the 1157 bulb instead.
The 1157 is an ANSI-standard dual-filament bulb rated at 12V with a 21W primary filament and a 5W secondary filament, fitted with a BAY15d bayonet base.
The BAY15d base on the 1157 features two contacts at offset pin positions, a physical distinction that prevents it from being seated in a BA15s socket designed for the 1156.
Although both the 1156 and 1157 share a 21W rating on their primary filament, the dual-filament construction of the 1157 makes it a different component from the single-filament 1156.
The change in bulb type between the 1979 and 1980 model years reflects a shift from a dual-filament to a single-filament back up light configuration in the Subaru DL.