Renault R12 Back Up Light Bulb Size

The Renault R12 back up light uses bulb size P21W or 1156 depending on the specific version of the vehicle. Data for the bulb sizes covers the range from 1973 to 1977.

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
1973-1977	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 listed for the back up light across all model years of the Renault R12 covered in these specifications.
The 1156 bulb follows the ANSI standard, which is the North American classification system used in the United States and Canada.
It operates on a 12-volt electrical system and draws 21 watts, placing it in the range typical of single-function automotive signal and reverse lighting.
The 1156 uses a single filament, meaning it serves one lighting function only, which is consistent with its application as a dedicated back up light bulb.
The base type is BA15s, a bayonet-style mount with a 15mm collar and a single locating pin, which locks the bulb into the socket with a push-and-twist motion.
The Renault R12 used the 1156 bulb for the back up light across the 1973-1977 model years, indicating a consistent socket and electrical specification throughout that production span.
The BA15s base is not interchangeable with the BA15d base, which carries two offset pins. Substituting a dual-pin bulb in a single-pin socket is not possible without modification.
The 1156 bulb is also commonly referenced under the trade designations P21W and 7506 in European and international markets, though these share the same core electrical and base specifications.