Mitsubishi Fuso FK Back Up Light Bulb Size

The Mitsubishi Fuso FK back up light uses P21W and 1156 bulb sizes for the rear illumination system. Data for the specified components covers the range from 1986 through 1998.

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
1986-1998	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 Mitsubishi Fuso FK uses the 1156 bulb for its back up light across all listed model years, spanning 1986-1998.
The 1156 is an ANSI-standardized bulb type, meaning its physical and electrical specifications conform to a defined industry standard recognized in the United States and Canada.
The 1156 bulb operates on a 12-volt electrical system and draws 21 watts, which is typical for incandescent automotive signal and reverse lighting applications.
The 1156 uses a BA15s bayonet base, a single-contact mount where the "s" denotes a single pin, distinguishing it from double-contact bayonet variants.
Because the 1156 is a single-filament bulb, it serves only one lighting function per socket, which is consistent with its dedicated use in a back up light application.
The BA15s bayonet base requires a quarter-turn insertion to lock into the socket, a mechanical fitment detail relevant when sourcing a replacement for the Mitsubishi Fuso FK.
The 1156 is sometimes marketed under related designations such as 7506 or P21W in international contexts, though these share the same core electrical and base specifications.
A common interchangeability concern with the 1156 involves confusion with the 1157 bulb, which shares a similar base housing but uses a BA15d double-contact base with two filaments and is not a compatible substitute in a single-filament socket.