Pontiac Tempest Map Light Bulb Size

The Pontiac Tempest Map Light utilizes bulb sizes 89 and 1004 for interior illumination. Data for the specified components covers the period from 1962 through 1970.

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
1969-1970	1004
1962-1968	89

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). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W.	89

Other Locations

Additional Notes

The Pontiac Tempest map light bulb specifications cover model years 1962 through 1970, with two distinct bulb types used across that span.
The bulb 89 is the more frequently specified type, appearing in the Pontiac Tempest from 1962 through 1968, a run of seven consecutive model years.
The 89 bulb follows the ANSI standard recognized in both the United States and Canada, operates at 12 volts, and draws 13 watts through a single filament.
Its BA15s bayonet base is a single-contact fitting, which is a defining physical characteristic that distinguishes it from dual-contact bayonet bases used on other bulb types.
The 89 is classified as a lower wattage variant of the 1156, meaning it shares the same base type and general construction but produces less light output due to its reduced wattage.
For the 1969-1970 Pontiac Tempest, the map light specification shifts to the 1004 bulb, which differs from the 89 in both filament count and base type.
The 1004 operates at 12 volts with a dual-filament configuration rated at 21/5 watts, where each wattage figure corresponds to one of the two filaments.
The 1004 uses a BAY15d bayonet base, a dual-contact offset fitting that is physically incompatible with the BA15s socket used by the 89 bulb.
The 1004 is described as a variant of the 1157, indicating a shared design lineage, though the two are not identical and are not interchangeable without verification of exact specifications.
Because the 89 and 1004 use different base types, a bulb from the 1962-1968 specification cannot be substituted into a 1969-1970 socket, and vice versa.