Geo Metro front and rear turn signal bulbs utilize 1156 and 1157 sizes, with the front turn signal bulb measuring 1156 and the rear turn signal bulb available in both 1156 and 1157 configurations. The replacement chart covers vehicle production spanning 1989 to 1997, detailing bulb size specifications across these years.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The 1156 is a single-filament bulb operating at 12V and 21W, fitted with a BA15s bayonet base, and conforming to the ANSI standard used in the United States and Canada.
The 1157 is a dual-filament bulb operating at 12V with filaments rated at 21W and 5W respectively, fitted with a BAY15d bayonet base, and also conforming to the same ANSI standard.
The BA15s and BAY15d bayonet bases are not interchangeable. The BA15s base has a single locating pin, while the BAY15d base has two offset pins, meaning 1156 and 1157 bulbs cannot be substituted for one another without a socket mismatch.
The Geo Metro uses the 1156 bulb across all model years from 1989-1997 for the front turn signal position.
The rear turn signal position of the Geo Metro uses two different bulb types depending on the model year, making year verification necessary before replacement.
The 1157 bulb is specified for the rear turn signal on the 1990-1992 Metro, while the 1156 is specified for 1989 and 1993-1997.
Because the 1157 carries a secondary 5W filament, its BAY15d socket is wired to support two independent circuits, a configuration absent from the single-filament 1156 and its BA15s socket.