The Buick Terraza front turn signal requires a 3157NA bulb size while the rear turn signal uses a 3157 bulb size. The replacement chart covers 2005 to 2007 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 3157NA and 3157 are both ANSI-standardized T25 dual-filament wedge bulbs rated at 12V with a 27W high filament and 7W low filament, making them the bulb types specified across all front and rear turn signal positions on the Buick Terraza for the 2005-2007 model years.
The dual-filament design of both bulb types means a single bulb serves two brightness levels, a configuration commonly used when one position functions as both a turn signal and a parking or running light.
The front turn signal on the 2005-2007 Buick Terraza calls for the 3157NA, which is distinguished from the standard 3157 by its natural amber-tinted glass envelope.
The natural amber glass of the 3157NA produces an amber-colored output without relying on an amber-colored lens, a characteristic relevant to housings that use a clear or white lens at the front turn signal position.
The rear turn signal on the 2005-2007 Buick Terraza uses the 3157, which has a clear glass envelope rather than amber-tinted glass.
Although the 3157NA and 3157 share identical electrical ratings, base type, and physical construction, substituting one for the other at the front position may affect the color output of the turn signal if the housing lens does not itself provide amber filtration.
Both bulb types conform to ANSI standards applicable in the United States and Canada, indicating a standardized base and filament specification that allows for cross-manufacturer sourcing within that designation.