Pontiac Chieftain Dome Light Bulb Size

The Pontiac Chieftain dome light requires a 1004 bulb size for proper illumination within the interior cabin area. Data for the specified component covers the range from 1955 through 1958.

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
1955-1958	1004

Bulb Specifications

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

Other Locations

Additional Notes

The 1004 bulb is the specified dome light bulb for the Pontiac Chieftain across the 1955-1958 model years.
The 1004 is an ANSI-standardized bulb type, meaning its physical and electrical characteristics conform to a defined North American standard recognized in both the United States and Canada.
The 1004 uses a BAY15d bayonet base, which is a double-contact bayonet mount with offset pins. The offset pin arrangement prevents incorrect insertion orientation.
The 1004 is a dual-filament bulb, meaning it contains two separate filaments within a single envelope, each operating at a different wattage.
The 1004 operates at 12 volts with a 21/5 watt output, where the two wattage values correspond to its two filaments respectively.
The 1004 is described as a variant of the 1157 bulb. The 1157 is a widely used automotive bulb sharing the same BAY15d base type, though the two are not necessarily interchangeable due to potential differences in wattage and fitment tolerances.