Peterbilt 388 Back Up Light Bulb Size

The Peterbilt 388 back up light utilizes a 1156 bulb size for the specific lighting component located at the rear of the vehicle. Available data covers the time range from 2008 through 2015 for the specified truck series.

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
2011-2015	1156
2008-2009	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 Peterbilt 388 uses the 1156 bulb across all specified model years for the back up light position.
The 1156 is an ANSI-standardized bulb type, meaning its physical and electrical specifications are governed by a recognized North American standard shared across the United States and Canada.
The 1156 operates on a 12-volt electrical system and draws 21 watts, which is consistent with standard incandescent automotive lighting output.
The bulb uses a BA15s bayonet base, a single-contact mount where the "s" designation indicates a single pin rather than the offset dual-pin arrangement found on related bayonet types such as the 1157.
Because the 1156 is single-filament, it serves only one lighting function per socket, unlike dual-filament alternatives that can handle two functions, such as stop and tail, within a single housing.
The BA15s base is not interchangeable with the BA15d base used on dual-filament bulbs, even though the physical socket size is similar, as the pin configuration differs.
The specified model years for the Peterbilt 388 back up light run from 2008-2015, with the 1156 bulb size applying uniformly across that range.