American Motors Pacer Map Light Bulb Size

The American Motors Pacer map light utilizes bulb sizes 1004 and 561 for interior illumination. Data for the specified lighting components covers the range from 1975 to 1980.

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
1980	1004
1975-1979	561

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Dual-filament bulb with BAY15d bayonet base. Variant of 1157. 12V, 21/5W.	1004
ANSI standard (US & Canada). Festoon bulb, 44mm length, end-cap contacts. 12V, 12W.	561

Other Locations

Additional Notes

The bulb type 561 is the most frequently specified map light bulb for the American Motors Pacer, covering the 1975-1979 model years.
The 561 is a festoon-style bulb, meaning it is cylindrical in form and makes electrical contact through metal caps at each end rather than through a base socket.
The 561 operates at 12 volts and draws 12 watts, placing it in a moderate output range typical of interior courtesy and map lighting applications.
The 561 measures 44mm in length, which is a critical fitment factor, as festoon bulbs must match the physical span of the holder to make proper contact at both ends.
The 1980 Pacer map light uses the 1004 bulb, which differs from the 561 used in all prior model years listed.
The 1004 uses a BAY15d bayonet base, a two-pin offset base that physically prevents incorrect insertion into the socket.
The 1004 is a dual-filament bulb rated at 12 volts with a 21/5 watt output, meaning it carries one higher-wattage filament and one lower-wattage filament within the same envelope.
The 1004 is described as a variant of the 1157, indicating shared electrical and base characteristics, though the two are not necessarily interchangeable without confirming socket and voltage compatibility.
Both the 561 and 1004 conform to ANSI standards applicable in the United States and Canada.
The shift from a festoon-type bulb to a bayonet-base dual-filament bulb between the 1979 and 1980 model years reflects a change in socket design that makes the two bulb types mutually incompatible.