Kenworth T300 Back Up Light Bulb Size

The Kenworth T300 back up light uses bulb size 1156 or P21W depending on the specific configuration of the vehicle. Data for the lighting components covers the range from 1995 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
1995-1997	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 1156 is the sole bulb type listed for the Kenworth T300 backup light across the 1995-1997 model years.
The 1156 is an ANSI-standardized bulb recognized in both the United States and Canada, meaning it conforms to a defined set of electrical and physical standards shared across those markets.
It is a single-filament bulb, which means it serves one lighting function rather than combining two, such as stop and tail, into a single unit.
The 1156 uses a BA15s bayonet base, a mount type characterized by a 15mm base width and a single locating pin, which locks the bulb into its socket with a push-and-twist motion.
The bulb operates at 12 volts and draws 21 watts, figures consistent with standard automotive electrical systems and typical backup light output levels.
Because the BA15s base has only one pin, it is not interchangeable with the BA15d base, which carries two offset pins and is found on dual-filament bulbs such as the 1157.