Peterbilt 389 Back Up Light Bulb Size

The Peterbilt 389 back up light uses 1156 and P21W bulb sizes for the exterior lighting components. Available data covers the period from 2008 through 2017 for the specified vehicle.

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
2011-2017	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 389 uses the 1156 bulb for its back up light across all listed model years from 2008-2017.
The 1156 is an ANSI-standardized bulb type, meaning its specifications are governed by a recognized North American standard applicable in both the United States and Canada.
The 1156 is a single-filament bulb, which distinguishes it from dual-filament types such as the 1157 that serve multiple lighting functions from one housing.
The 1156 operates at 12 volts and 21 watts, placing it within the range typical of standard automotive incandescent bulbs used in signaling and reversing applications.
The 1156 uses a BA15s bayonet base, where "BA15s" denotes a bayonet cap with a 15mm collar and a single contact pin at the base.
The single-contact BA15s base of the 1156 is not interchangeable with the BA15d base found on dual-filament bulbs, as the pin configuration differs between the two types.