The GMC Sonoma brake light uses 3057 and 2057 bulb sizes depending on the specific production version of the vehicle. Available information covers the time period from 1991 through 2004 for the specified components.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The GMC Sonoma brake light circuit relies on two distinct bulb types across its production run: the 3057 for 1994-2004 models and the 2057 for 1991-1993 models. These two types are not interchangeable despite their similar dual-filament design, as they use different base configurations.
The 3057 is a dual-filament wedge bulb built to the T25 form factor, operating at 12V with a 27W high filament and a 7W low filament. The wedge base design means it is retained by friction rather than a locking bayonet mechanism.
The 2057 uses a BAY15d bayonet base, which requires a twist-and-lock installation. It operates at 12V with filaments rated at 26.9W and 8W, and it is described as a brighter variant of the 1157 bulb type.
Because the 3057 uses a wedge base and the 2057 uses a BAY15d bayonet base, the two bulb types require physically different sockets. A 1991-1993 Sonoma brake light socket is not compatible with the 3057 used in 1994-2004 models.
The center high mount stop light (CHMSL) on the GMC Sonoma uses one of two bulb types depending on the model year: the 211-2 festoon bulb or the 921 wedge bulb. These are also not interchangeable with each other or with the brake light bulbs.
The 211-2 is a festoon bulb with a 41mm length and an SV8.5 base, rated at 12V and 12W. It is a single-filament type used exclusively for the CHMSL function in the years it appears.
The 921 is a single-filament wedge bulb built to the T15 form factor, rated at 12V and 16W. It produces more wattage than the 211-2 despite both serving the same CHMSL function on the Sonoma.
The CHMSL socket type changed between certain model years. The 1997-2004 Sonoma used the 211-2 in most years, while 1998-2000 models used the 921. The socket designs for festoon and wedge bulbs are physically distinct, so the bulb type must match the socket present in the specific vehicle.
All four bulb types listed in the specifications conform to ANSI standards applicable in both the United States and Canada, meaning they share standardized electrical and physical ratings across those markets.
The dual-filament design of both the 3057 and 2057 allows a single bulb to serve both the brake light and tail light functions, with the higher-wattage filament activating under braking and the lower-wattage filament providing the running light.