Mazda GLC Back Up Light Bulb Size

The Mazda GLC back up light requires bulb size 1156 or P21W depending on the specific vehicle configuration. Data for the bulb size chart covers the range from 1977 to 1985.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

Bulb Size by Year Range

Years	Bulb Size
1984-1985	1156
1977-1982	1156

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

Other Locations

Additional Notes

The 1156 is the sole back up light bulb size listed for the Mazda GLC across all specified model years.
The 1156 is a single-filament bulb, meaning it serves one lighting function rather than combining two, such as stop and tail duties, into a single unit.
The 1156 operates at 12 volts and 21 watts, which is consistent with standard 12V automotive electrical systems.
The 1156 uses a BA15s bayonet base, a single-contact mount that locks into the socket with a twist rather than a threaded connection.
The 1156 conforms to ANSI standards and carries recognition in both the United States and Canada.
The Mazda GLC back up light bulb size remains the 1156 from 1977-1982 and again in 1984-1985, with no variation across those years.
Because the 1156 is a single-filament type, it is not interchangeable with dual-filament bulbs such as the 1157, which shares a similar bayonet base style but carries a second contact pin and filament.