Dodge Royal Map Light Bulb Size

The Dodge Royal map light utilizes bulb size 90 and bulb size 1004 for the interior lighting system. Data for the specific bulb requirements covers the range from 1956 to 1959.

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
1957-1959	90
1956	1004

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 13W.	90
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W.	1004

Other Locations

Additional Notes

The Dodge Royal map light draws from two ANSI-standard bulb types across its model years, both rated at 12 volts and both using bayonet-style bases.
The bulb 90 is a single-filament type mounted on a BA15s bayonet base, rated at 13 watts. The BA15s base features a single contact pin, which physically prevents substitution with dual-filament bulb types that use offset pins.
The Dodge Royal (1957-1959) uses the 90 bulb for the map light position.
The bulb 1004 is a dual-filament type mounted on a BAY15d bayonet base, rated at 21/5 watts. The two wattage values correspond to its two separate filaments, each serving a distinct circuit function.
The Dodge Royal (1956) uses the 1004 bulb for the map light position.
The 1004 is noted as a variant of the 1157 bulb. Both share the BAY15d base and dual-filament design, though they differ in wattage output, which means the two are not direct substitutes in all applications.
The BA15s base of the 90 and the BAY15d base of the 1004 are physically distinct and not interchangeable. The BAY15d base uses offset pins to enforce correct polarity orientation, while the BA15s base does not.
The shift from the 1004 in 1956 to the 90 in 1957 represents a change from a dual-filament to a single-filament map light bulb in the Dodge Royal.