Kenworth T400 front turn signal bulbs use 1157 size while rear turn signal bulbs use 1156 or 1157 size. The replacement chart covers vehicle production from 1982 to 1997 with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Kenworth T400 front turn signal uses the 1157 bulb across all listed model years from 1982 to 1997.
The 1157 is a dual-filament bulb operating at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base.
The BAY15d base features two offset pins, which physically prevents it from being interchanged with single-filament bulbs that use the BA15s base.
The rear turn signal on the Kenworth T400 uses either the 1156 or the 1157 depending on the model year, making direct substitution between years inadvisable without confirming the socket type.
The 1156 is a single-filament bulb operating at 12V with a 21W output, mounted on a BA15s bayonet base.
For the rear turn signal, the 1156 is specified for 1989, 1984, and the 1993-1997 model years, while the 1157 is specified for 1982, 1990, and 1992.
Although the 1156 and 1157 share the same 21W primary filament rating, their base types differ, and the two bulbs are not interchangeable.
Both the 1156 and 1157 conform to ANSI standards recognized in the United States and Canada.