Peterbilt 340 Back Up Light Bulb Size

The Peterbilt 340 back up light requires bulb size 1156 or P21W depending on the specific configuration of the vehicle. Data for the bulb specifications covers the range from 2007 to 2009.

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
2007-2009	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 specified back up light bulb size for the Peterbilt 340 across the 2007-2009 model years.
The 1156 bulb follows the ANSI standard, which is the recognized specification body for the United States and Canada.
It is a single-filament bulb, meaning it serves one lighting function rather than combining two, such as stop and tail.
The 1156 uses a BA15s bayonet base, a single-contact mount where the bulb locks into the socket with a twist.
The bulb operates at 12 volts, consistent with standard automotive electrical systems.
Its rated wattage is 21W, which reflects the power draw of a single-filament reverse light application.
The BA15s base designation is not interchangeable with the BA15d double-contact bayonet base, and substituting one for the other is not compatible with this fitment.