The Peterbilt 340 front and rear turn signal bulbs both utilize a 2057 size bulb for proper operation. The replacement chart covers vehicle production spanning 2007 to 2009.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 2057 bulb follows the ANSI standard recognized in both the United States and Canada, making it a regulated specification rather than a proprietary automotive part.
The Peterbilt 340 (2007-2009) uses the 2057 bulb size for both front and rear turn signal positions.
The 2057 is a dual-filament bulb, meaning it carries two separate filaments within a single housing to serve two distinct lighting functions at different wattages.
The 2057 operates on a 12-volt system with a wattage split of 26.9W for the high-intensity filament and 8W for the low-intensity filament.
The 2057 uses a BAY15d bayonet base, which is an offset dual-contact base designed to allow only one correct insertion orientation, preventing incorrect filament-to-circuit alignment.
The 2057 is described as a brighter variant of the 1157 bulb. While the two share the same BAY15d base and are physically interchangeable in many housings, the 2057 produces greater output on its high-intensity filament than the 1157.
Because the 1157 and 2057 share the same base type, substitution between them is physically possible, though the wattage and brightness output will differ depending on which is installed.