The Hummer H3T uses a 3157 bulb size for brake applications and a 912 bulb size for the center high mount stop light. The replacement chart covers 2009 to 2010 vehicle production 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 Hummer H3T uses the 3157 bulb for its brake lights across the 2009-2010 model years. This bulb follows the ANSI standard applicable in both the United States and Canada.
The 3157 is a dual-filament T25 wedge bulb rated at 12V with a wattage split of 27W and 7W. The dual-filament design allows a single bulb to serve two functions, typically a lower-intensity running mode and a higher-intensity braking mode.
The center high mount stop light on the H3T for the 2009-2010 model years takes the 912 bulb, which is a separate specification from the standard brake bulb position.
The 912 is a single-filament T15 wedge bulb rated at 12V and 12W. It conforms to the same ANSI standard as the 3157 and is recognized in both the United States and Canada.
The 912 bulb is a variant of the 921. These two types share the same T15 wedge form factor but differ in wattage, which makes them non-identical substitutes despite their physical similarity.