The Mazda GLC front turn signal requires a 1157 bulb size, while rear turn signals use either 1156 or 1157 bulb sizes. The replacement chart covers 1977 through 1985 model years with corresponding bulb specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mazda GLC front turn signal uses the 1157 bulb across all listed model years from 1977-1985, making it the sole front turn signal bulb type in these specifications.
The 1157 is a dual-filament bulb rated at 12V with a 21W main filament and a 5W secondary filament, mounted on a BAY15d bayonet base, and classified under the ANSI standard applicable in the US and Canada.
The BAY15d base features two offset pins at different heights, which physically prevents incorrect installation of a single-filament bulb in a dual-filament socket.
The rear turn signal on the Mazda GLC uses the 1156 bulb for 1977-1978 and 1980-1985, while the 1979 model year uses the 1157 instead.
The 1156 is a single-filament bulb rated at 12V and 21W, mounted on a BA15s bayonet base, and also falls under the ANSI standard for the US and Canada.
The BA15s base used by the 1156 has two pins at equal heights, distinguishing it from the BAY15d base of the 1157. The two bases are not interchangeable despite their similar appearance.
Although the 1157 and 1156 share the same 21W main filament wattage, substituting a 1156 for a 1157 in a dual-filament application would result in the loss of the secondary 5W circuit function.
The 1979 rear turn signal position is the only instance in these specifications where the 1157 appears in a rear application, while all other listed rear turn signal years call for the 1156.