Mitsubishi Diamante Back Up Light Bulb Size

The Mitsubishi Diamante back up light utilizes 921, 1156, and P21W bulb sizes depending on the specific production version. Available information covers a time range from 1992 through 2004.

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
2002-2004	921
1997-2001	1156
1992-1996	921

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). 12V, 16W.	921
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 21W.	1156

Other Locations

Additional Notes

The Mitsubishi Diamante uses two distinct back up light bulb types across its model years: the 921 and the 1156, both of which are ANSI-standardized bulbs for the US and Canadian markets.
The 921 is a T15 wedge-base bulb rated at 12V and 16W. Its wedge-style base requires no locking pins, as the base itself is pinched into the socket to make electrical contact.
The 1156 is a single-filament bulb with a BA15s bayonet base, rated at 12V and 21W. The BA15s designation indicates a single-contact bayonet fitting with a 15mm base width.
The 1156 draws 21W compared to the 921's 16W, meaning the two bulb types are not electrically equivalent and are not interchangeable between sockets designed for one or the other.
Beyond the wattage difference, the 921 and 1156 use entirely different base styles, a wedge versus a bayonet, which makes physical interchangeability impossible without socket modification.
The Mitsubishi Diamante (1992-1996) uses the 921 bulb for the back up light position.
Model years 1997-2001 use the 1156 bulb, representing a shift to the higher-wattage bayonet-base type.
The 2002-2004 Diamante returns to the 921 wedge bulb for the back up light position.