Chevrolet Colorado Back Up Light Bulb Size

Additional Notes

• The Chevrolet Colorado backup light specifications reference two distinct bulb types across the model's production years: the 921 and the 3057, both of which conform to ANSI standards applicable in the United States and Canada.
• The 921 is a single-filament wedge bulb rated at 12 volts and 16 watts, classified under the T15 form factor. Its wedge-style base requires no separate metal connector, as the glass envelope itself serves as the contact point within the socket.
• The 3057 is a dual-filament wedge bulb rated at 12 volts with two wattage outputs: 27 watts on the high filament and 7 watts on the low filament. It follows the T25 form factor, which is physically larger than the T15 used by the 921.
• The presence of two filaments in the 3057 is a design feature that allows a single bulb to serve multiple lighting functions at different intensities, though in the Colorado's backup light application, only the relevant filament circuit is engaged.
• The Chevrolet Colorado (2015-2024) uses the 921 bulb for the backup light position.
• Model years 2004-2012 use the 3057 bulb instead, reflecting a different socket and electrical configuration from the generation that followed.
• Because the 921 and 3057 differ in both physical size and filament count, the two bulb types are not interchangeable between the two generation groups.
• The T25 housing of the 3057 is larger than the T15 housing of the 921, meaning a 3057 bulb will not seat correctly in a socket designed for the 921, and vice versa.