GMC Envoy front turn signal bulbs use 3457 size while rear turn signal bulbs use 3057 or 3157 size. The replacement chart covers 2002 through 2009 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 GMC Envoy uses three bulb types across its turn signal positions: 3457 for the front and either 3057 or 3157 for the rear, depending on the model year.
All three bulb types, the 3457, 3057, and 3157, share the same T25 wedge form factor, dual-filament design, 12V operating voltage, and 27W/7W wattage rating.
The dual-filament construction in these bulbs allows a single unit to serve two lighting functions, typically combining the turn signal and parking light roles within one housing.
All three bulb types conform to ANSI standards recognized in both the United States and Canada.
The front turn signal position on the GMC Envoy uses the 3457 bulb consistently across the full 2002-2009 model year range covered by the specifications.
The rear turn signal position transitioned from the 3157 bulb in 2002-2003 to the 3057 bulb in 2004-2009, meaning the two rear bulb types are not interchangeable across all model years despite sharing the same wattage and form factor.
Although the 3057 and 3157 bulbs share identical T25 wedge bases and 27W/7W ratings, they carry distinct ANSI designations and are specified separately by model year, indicating a fitment distinction that warrants attention during replacement.
The 27W filament in each bulb corresponds to the higher-intensity turn signal function, while the 7W filament serves the lower-intensity parking or position light function.