Plymouth Sapporo Back Up Light Bulb Size

The Plymouth Sapporo back up light requires bulb size P21W or 1156 depending on the specific version. Data for the bulb sizes covers the range from 1978 to 1983.

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
1978-1983	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 Plymouth Sapporo uses the 1156 bulb for the back up light across all model years covered in the specifications, spanning 1978-1983.
The 1156 is a single-filament bulb, meaning it serves one lighting function rather than combining two, such as stop and tail duties, into a single unit.
The 1156 operates at 12 volts and 21 watts, which is consistent with standard automotive electrical systems of that era.
The 1156 carries the BA15s bayonet base designation, where "BA15s" indicates a 15mm bayonet fitting with a single contact pin at the base.
The 1156 is an ANSI-standardized bulb, recognized across the United States and Canada under a shared specification, which reflects broad regional availability.
Because the 1156 is a single-filament type, it is not interchangeable with the visually similar 1157, which carries a dual-filament design and a different base configuration despite sharing the same bayonet mount style.