The Hummer H3T uses 3157 bulbs for both front and rear turn signal applications. Replacement specifications in the chart cover 2009 to 2010 model years.
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 across all listed turn signal positions for the 2009-2010 model years.
The 3157 is an ANSI-standardized bulb type, meaning its specifications are governed by a formal industry standard recognized in both the United States and Canada.
The 3157 is a dual-filament bulb, which means it contains two separate filaments operating at different wattages within a single housing, allowing it to serve more than one lighting function.
The two filaments in the 3157 operate at 27 watts and 7 watts respectively, with the higher-wattage filament typically associated with the active turn signal flash and the lower-wattage filament used for a secondary function such as a parking or running light.
The 3157 follows the T25 wedge form factor, a designation that describes the shape and base type of the bulb used for physical installation.
The bulb operates on a 12-volt electrical system, consistent with the standard automotive voltage found in passenger vehicles.
The 3157 is used in both the front and rear turn signal positions on the Hummer H3T, indicating that the same bulb type serves both ends of the vehicle across the listed model years.
Because the 3157 is a dual-filament type, substituting it with a single-filament equivalent would result in the loss of one of its two lighting functions at that position.