Peterbilt 385 Back Up Light Bulb Size

The Peterbilt 385 back up light utilizes 1156 and P21W bulb sizes for various lighting applications on the vehicle. Data for the specified components covers the range from 1995 through 2008.

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
1998-2008	1156
1997	1156
1997	1156 (With Halogen Capsule Headlamps)
1996	1156
1996	1156 (With 4 Round Headlamps)
1995	1156
1995	1156 (With Halogen Capsule Headlamps)

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 385 uses the 1156 bulb for its back up light across all listed model years from 1995 to 2008.
The 1156 is an ANSI-standard bulb recognized in both the United States and Canada, operating at 12 volts and 21 watts.
As a single-filament bulb, the 1156 is designed to serve one lighting function, which makes it a typical choice for dedicated back up light applications rather than combined stop/tail functions.
The 1156 uses a BA15s bayonet base, a single-contact mount where the "s" denotes a single pin, distinguishing it from the dual-contact BA15d base used in two-filament variants such as the 1157.
The BA15s base is not interchangeable with BA15d sockets, so substituting a dual-contact bulb such as the 1157 in a single-contact socket is not compatible without modification.
The 1996 Peterbilt 385 with 4 Round Headlamps and the 1995 and 1997 models with Halogen Capsule Headlamps all share the same 1156 back up light bulb specification as their standard counterparts, indicating that headlamp configuration does not affect back up light fitment.