Kenworth C500 Back Up Light Bulb Size

The Kenworth C500 back up light utilizes 1156 and P21W bulb sizes for the rear illumination system. Data for the specified components covers the time range from 1981 to 1997.

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
1981-1997	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 C500 uses the 1156 bulb for the back up light across all listed model years, spanning 1981-1997.
The 1156 is a single-filament bulb, meaning it serves one lighting function rather than combining two, such as stop and tail, into a single unit.
It operates on a 12-volt electrical system and draws 21 watts, which is consistent with standard incandescent automotive lighting of that era.
The 1156 uses a BA15s bayonet base, where "BA15s" denotes a bayonet fitting with a 15mm collar and a single contact pin at the base.
The single-pin BA15s base is not interchangeable with the BA15d base, which carries two offset pins and is found on dual-filament bulbs such as the 1157.
The 1156 carries ANSI standardization, indicating its electrical and physical specifications conform to a defined North American standard recognized in both the United States and Canada.
Because the 1156 is an ANSI-standardized type, equivalent bulbs from different manufacturers sharing the same designation are expected to meet the same voltage, wattage, and base specifications.