Peterbilt 335 Back Up Light Bulb Size

The Peterbilt 335 back up light utilizes bulb size 1156 and bulb size P21W for illumination. Data for the specified lighting components covers the range from 2005 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
2005-2009	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 an ANSI-standardized bulb type recognized across the United States and Canada, operating at 12 volts with a power draw of 21 watts through a single filament.
The BA15s bayonet base on the 1156 bulb features a single contact pin offset to one side, which physically prevents incorrect insertion and distinguishes it from dual-contact bayonet variants.
The Peterbilt 335 uses the 1156 bulb for its backup light across the 2005-2009 model years.
Because the 1156 is a single-filament design, it serves dedicated single-function applications such as reverse lighting, as opposed to dual-filament bulbs that handle two functions from one housing.
The BA15s base type is not interchangeable with the BA15d base, which carries two contact pins. Substituting a BA15d bulb into a BA15s socket is not possible without modification.
At 21 watts on a 12-volt circuit, the 1156 draws approximately 1.75 amperes, a figure relevant when assessing socket and wiring load compatibility.