The Buick Rainier front turn signal requires a 3757NA bulb size while the rear turn signal uses a 3157 bulb size. The replacement chart covers 2004 through 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 Buick Rainier uses two distinct bulb types across its turn signal positions for the 2004-2007 model years: the 3757NA for the front and the 3157 for the rear.
Both the 3757NA and 3157 are ANSI-standardized dual-filament wedge bulbs in the T25 form factor, operating on a 12-volt electrical system.
A dual-filament bulb contains two separate filaments within a single housing, allowing one bulb to serve two functions, typically a lower-intensity running or parking light and a higher-intensity signal flash.
The 3157 rear turn signal bulb carries a rated output of 27W on its high-intensity filament and 7W on its low-intensity filament, reflecting its dual-function role.
The 3757NA front turn signal bulb features natural amber glass, meaning the amber color is produced by the glass envelope itself rather than by a coated or painted lens.
The "NA" suffix in the 3757NA designation specifically denotes the natural amber glass construction, which distinguishes it from clear-glass variants in the same bulb family.
Because the 3757NA produces its amber color through the glass itself, substituting a clear-glass equivalent in the Rainier's front turn signal position would alter the emitted light color at that position.
Both bulb types conform to ANSI standards applicable in the United States and Canada, indicating a shared regulatory framework for their electrical and photometric performance.
The T25 wedge base is a common automotive base type that seats directly into a socket without a separate metal base, relying on the glass envelope's tapered sides for retention.
Although the 3757NA and 3157 share the same T25 form factor and 12-volt rating, they are not interchangeable between the front and rear positions on the Rainier due to differences in glass color and wattage.