The INFINITI M30 brake light utilizes a 1157 bulb size for the specific lighting components located at the rear of the vehicle. Data for the specified lighting equipment covers the range from 1990 to 1992.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 1157 is a dual-filament bulb operating at 12V with a 21W high filament and a 5W low filament, mounted on a BAY15d bayonet base. The two filaments serve separate functions within a single housing, with the higher-wattage filament activating under braking and the lower-wattage filament serving as a running light.
The BAY15d bayonet base on the 1157 features offset pins, which physically prevent incorrect installation. A bulb with symmetrically placed pins is not interchangeable with this socket.
The 921 is a single-filament wedge-base bulb of the T15 type, rated at 12V and 16W. Wedge-base bulbs rely on the tension of the socket contacts against the glass envelope rather than a separate base component for retention.
Both the 1157 and 921 conform to ANSI standards applicable in the United States and Canada, indicating standardized electrical and physical specifications across those markets.
The INFINITI M30 uses the 1157 for the standard brake lights across the 1990-1992 model years, while the 921 is designated specifically for the Center High Mount Stop Light across the same span.
The 1157 and 921 are not interchangeable with each other. The 1157 uses a bayonet base and the 921 uses a wedge base, and their wattage ratings and filament configurations differ as well.