Dodge Diplomat Back Up Light Bulb Size

The Dodge Diplomat back up light utilizes P21W and 1156 bulb sizes depending on the specific production version. Available data for the bulb sizes covers the range from 1977 to 1989.

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
1977-1989	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 Dodge Diplomat uses the 1156 bulb for the back up light across all documented model years, spanning 1977-1989.
The 1156 is a single-filament bulb, meaning it serves one lighting function only, which in this application is the back up light.
The 1156 operates at 12 volts and 21 watts, placing it in the standard range for automotive reverse lighting.
The 1156 uses a BA15s bayonet base, a single-contact mount where the "s" denotes a single pin, as opposed to the dual-pin BA15d variant.
The BA15s base is not interchangeable with the BA15d base, and substituting one for the other is not possible without modification.
The 1156 conforms to ANSI standards recognized in both the United States and Canada, indicating a standardized specification rather than a proprietary one.
Because the 1156 is a widely standardized ANSI bulb, it is produced by numerous manufacturers, though the single-filament and BA15s base requirements remain fixed for correct fitment in the Dodge Diplomat.