Kenworth K150 Back Up Light Bulb Size

The Kenworth K150 back up light uses bulb size 1156 and bulb size P21W according to the provided specifications for the lighting components. Data for the lighting equipment covers the range from 1990 to 1994.

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
1990-1994	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 Kenworth K150 uses the 1156 bulb across all listed model years, spanning 1990-1994, for the back up light position.
The 1156 is a single-filament bulb, meaning it serves one lighting function only, which is consistent with its application in a dedicated back up light circuit.
The 1156 operates at 12 volts and 21 watts, placing it within the standard range for incandescent automotive signal and utility lighting.
The 1156 uses a BA15s bayonet base, where "BA15s" denotes a single-contact bayonet fitting with a 15mm base width, distinguishing it from dual-contact variants that are not interchangeable.
The 1156 conforms to ANSI standards recognized in both the United States and Canada, indicating a standardized specification shared across North American automotive applications.
Because the BA15s base is a single-contact design, substitution with visually similar bulbs using a BA15d dual-contact base would result in an incompatible fitment for the Kenworth K150.