Peterbilt 357 Back Up Light Bulb Size

The Peterbilt 357 back up light utilizes 1156 and P21W bulb sizes for the rear illumination system. Available information spans a range from 1986 through 2008 for the specified vehicle components.

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 4 Rectangular Headlamps)
1996	1156
1996	1156 (With Halogen Capsule Headlamps)
1995	1156
1995	1156 (With 4 Round Headlamps)
1994	1156
1994	1156 (With 4 Rectangular Headlamps)
1993	1156
1992	1156
1992	1156 (With Halogen Capsule Headlamps)
1991	1156
1990	1156
1990	1156 (With Halogen Capsule Headlamps)
1989	1156
1989	1156 (With 4 Round Headlamps)
1987-1988	1156
1987-1988	1156 (With 4 Rectangular Headlamps)
1986	1156
1986	1156 (With 4 Round 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 357 uses the 1156 bulb for the back up light position across every model year listed in the specifications, spanning 1986-2008.
The 1156 is a single-filament bulb, which is the standard construction for back up lights, as that circuit requires only one function: illumination when reverse gear is engaged.
The 1156 operates at 12 volts and 21 watts, placing it in the mid-range output category for incandescent automotive bulbs.
The 1156 uses a BA15s bayonet base, a single-contact fitting where the "s" denotes a single pin, distinguishing it from the dual-contact BA15d base used on two-filament bulbs.
The 1156 conforms to ANSI standards recognized in both the United States and Canada, meaning the bulb specification follows a regulated performance and dimensional standard rather than a proprietary one.
Several model years in the specifications carry sub-entries noting specific headlamp configurations, such as "With 4 Rectangular Headlamps," "With 4 Round Headlamps," and "With Halogen Capsule Headlamps." In all of these cases, the back up light bulb size remains 1156 regardless of headlamp type.
The 1156 is not interchangeable with the visually similar 1157 bulb. The 1157 uses a BA15d dual-contact base with two filaments, and its base pin arrangement differs from the single-contact BA15s socket used by the 1156.