Peterbilt 270 Back Up Light Bulb Size

The Peterbilt 270 back up light requires bulb size 1156 or P21W depending on the specific version of the component. Data for the bulb size covers the range from 2001 to 2003.

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
2001-2003	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 bulb type specified for the back up light on the Peterbilt 270 across the 2001-2003 model years.
The 1156 is an ANSI-standardized bulb type, meaning its physical and electrical characteristics conform to a defined North American standard recognized in both the United States and Canada.
The 1156 operates on a 12-volt electrical system and draws 21 watts, which is consistent with standard automotive incandescent back up light applications.
The 1156 uses a BA15s bayonet base, a single-contact fitting where the "s" designation indicates a single pin positioned symmetrically on the base, allowing only one rotational orientation during installation.
As a single-filament bulb, the 1156 is designed for functions requiring one consistent light output level, making it suited for dedicated back up light duty rather than dual-function applications such as combined stop and tail lighting.
The BA15s base of the 1156 is not interchangeable with the BA15d base found on dual-filament bulbs such as the 1157, as the pin configurations differ and the sockets are not compatible.