The Buick Somerset front and rear turn signal bulbs both utilize a 2057 size bulb for proper operation. The replacement chart covers 1986 to 1987 model years 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 Buick Somerset uses the 2057 bulb across both the front and rear turn signal positions for the 1986-1987 model years.
The 2057 is an ANSI-standardized bulb type recognized in both the United States and Canada.
It is a dual-filament bulb, meaning it contains two separate filaments within a single envelope, allowing it to serve more than one lighting function.
The 2057 uses a BAY15d bayonet base, a two-pin offset base design that ensures correct orientation during installation.
The bulb operates at 12 volts, consistent with standard automotive electrical systems.
Its two filaments draw 26.9 watts and 8 watts respectively, with the higher-wattage filament typically associated with the brighter turn signal or stop function.
The 2057 is a brighter variant of the 1157 bulb, sharing the same BAY15d base type, which means the two types are physically similar but not electrically identical due to differing wattage ratings.
Because of the wattage difference between the 2057 and 1157, substituting one for the other may affect circuit load and light output, particularly in systems with load-sensitive flasher units.