The Pontiac G3 brake light requires a 1157 bulb size for proper installation and function within the rear lighting assembly. Data for the specified component covers the range from 2009 to 2010.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Pontiac G3 uses the 1157 bulb for its brake lights across the 2009-2010 model years.
The 1157 is an ANSI-standardized dual-filament bulb, meaning it serves two lighting functions within a single unit, typically combining stop and tail light operation through separate filaments rated at 21W and 5W respectively.
The 1157 uses a BAY15d bayonet base, a two-pin offset bayonet mount designed to prevent incorrect installation by ensuring the bulb can only be seated in one orientation.
The dual-filament design of the 1157 is a common source of substitution errors, as single-filament bulbs sharing similar base types are not interchangeable with it without loss of function.
The center high mount stop light on the Pontiac G3 uses the 12961 bulb for the 2009-2010 model years, a different type from the main brake bulb.
The 12961 is a Philips part number designation for a miniature wedge bulb in the T10 form factor, operating at 12V and 5W.
The 12961 uses a W2.1x9.5d wedge base, which is a pinless design that relies on wire contacts along the sides of the bulb base for electrical connection and retention.
The T10 wedge format of the 12961 is physically incompatible with the BAY15d bayonet base of the 1157, making the two bulb types non-interchangeable despite both operating at 12V.