Kenworth K150 front and rear turn signal bulbs utilize 1157 and 1156 sizes, with the front requiring the 1157 bulb size exclusively. The replacement chart covers 1990 to 1994 model years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Kenworth K150 uses two distinct bulb types across its front and rear turn signal positions: the 1157 and the 1156, both governed by ANSI standards recognized in the United States and Canada.
The 1157 is a dual-filament bulb rated at 12V with a 21W primary filament and a 5W secondary filament, mounted on a BAY15d bayonet base. The dual-filament design allows a single bulb to serve two lighting functions simultaneously.
The 1156 is a single-filament bulb rated at 12V and 21W, mounted on a BA15s bayonet base. It serves only one lighting function per socket.
The BAY15d base of the 1157 and the BA15s base of the 1156 are physically distinct and not interchangeable, as the pin offset configuration of the BAY15d differs from the single-pin arrangement of the BA15s.
On the Kenworth K150, the front turn signal position uses the 1157 bulb consistently across all model years from 1990-1994.
The rear turn signal position does not follow a uniform specification across the same 1990-1994 span. The 1990 and 1994 model years use the 1157, while the 1991-1993 model years use the 1156.
Because the rear turn signal specification changed between 1990 and 1991, and again between 1993 and 1994, the correct bulb type for the rear position is year-dependent and requires verification before replacement.
A 1156 bulb cannot serve as a direct substitute in a socket designed for the 1157, as the differing base configurations and filament counts make them mechanically and functionally incompatible.