The Peterbilt 365 front and rear turn signal bulbs utilize 1157 or 2057 bulb sizes depending on configuration. The replacement chart covers vehicle production spanning 2008 to 2017 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 1157 is an ANSI-standard dual-filament bulb operating at 12V with a 21W high filament and 5W low filament, mounted on a BAY15d bayonet base. It serves both front and rear turn signal positions on the Peterbilt 365 across the 2011-2017 model years.
The 2057 is also an ANSI-standard dual-filament bulb with a BAY15d bayonet base, rated at 12V with a 26.9W high filament and 8W low filament. It is specified for both front and rear turn signals on the 2008-2009 Peterbilt 365.
Dual-filament bulbs such as the 1157 and 2057 serve two functions within a single housing. The higher-wattage filament activates for the turn signal flash, while the lower-wattage filament handles a secondary function such as a running or parking light.
Both the 1157 and 2057 share the BAY15d bayonet base, which features two offset pins that prevent incorrect insertion. This shared base type means the physical socket is the same between the two bulbs.
Although the 1157 and 2057 share the same base and voltage rating, the 2057 draws notably more wattage on both filaments. Substituting a 2057 into a socket designed for a 1157 may affect circuit load and flasher timing.
The front and rear turn signal positions on the Peterbilt 365 use identical bulb sizes within any given model year, meaning the same bulb type applies to both positions simultaneously.
A bulb change occurs between the 2009 and 2011 model years, where the specified size shifts from the 2057 to the 1157 for both the front and rear turn signal positions.