Mazda RX-7 Back Up Light Bulb Size

The Mazda RX-7 back up light utilizes 1156 and P21W bulb sizes for illumination across various production versions. Available data covers the specific range from 1979 through 1995.

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
1993-1995	1156
1979-1991	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 Mazda RX-7 uses the 1156 bulb for its back up light across all listed model years, spanning 1979-1995.
The 1156 is a single-filament bulb, meaning it serves one lighting function rather than combining two, such as stop and tail duties.
It operates on a 12-volt electrical system at 21 watts, which aligns with standard automotive low-voltage architecture.
The 1156 uses a BA15s bayonet base, where "BA15s" denotes a single-contact bayonet fitting with a 15mm base width.
The BA15s base type is not interchangeable with the BA15d double-contact bayonet base, which is found on dual-filament bulbs such as the 1157.
The 1156 carries ANSI standardization applicable to the United States and Canada, indicating it conforms to a defined set of electrical and physical tolerances within those markets.
Because the 1156 is a single-filament design, substituting a dual-filament bulb with a BA15d base into the same socket is not a compatible replacement, as the base contact configuration differs.
The consistent use of the 1156 across the Mazda RX-7 from 1979-1995 indicates that the back up light socket specification did not change throughout the vehicle's production run in the listed data.