Volkswagen Fastback Back Up Light Bulb Size

The Volkswagen Fastback back up light uses 1156 and P21W bulb sizes for the rear lighting system. Data for the lighting components covers the period from 1969 through 1973.

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
1969-1973	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 Volkswagen Fastback uses the 1156 bulb for the back up light across all listed model years, spanning 1969-1973.
The 1156 is an ANSI-standardized bulb, meaning its specifications are governed by a recognized North American standard applicable in both the US and Canada.
This bulb operates on a 12-volt electrical system and draws 21 watts, which is typical of incandescent automotive reverse lighting applications.
The 1156 is a single-filament bulb, meaning it serves only one lighting function, as opposed to dual-filament bulbs that handle two functions such as braking and running light simultaneously.
The BA15s designation refers to a bayonet-style base with a 15mm collar and a single locating pin, which locks the bulb into its socket with a push-and-twist motion.
The single-pin BA15s base is not interchangeable with the BA15d base, which carries two offset pins and is found on dual-filament bulbs such as the 1157. Substituting one for the other is not possible without modifying the socket.