Volvo 144 Back Up Light Bulb Size

The Volvo 144 back up light requires bulb size 1156 or P21W depending on the specific application. Data for the provided components covers the range from 1973 to 1974.

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
1973-1974	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 specified for the Volvo 144 backup light across the 1973-1974 model years.
The 1156 operates on a 12-volt electrical system and draws 21 watts, placing it in the standard incandescent range for single-circuit automotive lighting applications.
The 1156 uses a BA15s bayonet base, which is a single-contact bayonet fitting. The "s" in BA15s denotes a single contact pin, distinguishing it from the dual-contact BA15d base used in other bulb types.
As a single-filament bulb, the 1156 serves one lighting function only, which aligns with its application in a dedicated backup light rather than a combined stop/tail unit.
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 parameters shared across those markets.
The BA15s bayonet base requires a quarter-turn insertion method. Substituting a bulb with a BA15d base is not compatible, as the dual-pin base will not seat correctly in a single-contact socket.