Pontiac LeMans Map Light Bulb Size

The Pontiac LeMans map light requires bulb sizes 1004 and 89 for the interior illumination system. Available data for the specified components covers the period from 1963 through 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
1974	1004
1969-1970	1004
1963-1968	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 LeMans map light bulb specifications cover model years 1963 through 1980, with two distinct bulb types appearing across that span: the 1004 and the 89.
The bulb 89 is an ANSI-standardized single-filament lamp rated at 12V and 13W, fitted with a BA15s bayonet base. It is a lower wattage variant of the 1156 bulb family.
The bulb 1004 is an ANSI-standardized dual-filament lamp rated at 12V and 21/5W, fitted with a BAY15d bayonet base. It is a variant of the 1157 bulb family.
The BA15s base of the 89 and the BAY15d base of the 1004 are physically similar in size but are not interchangeable. The BAY15d base features offset pins to ensure correct polarity alignment for dual-filament operation, while the BA15s base has symmetrical pins suited only for single-filament use.
The Pontiac LeMans (1963-1968) uses the 89 bulb for the map light across six consecutive model years.
The 1004 bulb appears in the 1969 and 1970 model years, representing a shift from the single-filament 89 to a dual-filament lamp for the map light position.
The 1974 and 1980 model years also specify the 1004 bulb for the map light, consistent with the fitment established in 1969.
Because the 1004 is a dual-filament bulb and the 89 is a single-filament bulb, substituting one for the other is not supported by these specifications, despite both using visually similar bayonet-style bases.
Both the 89 and the 1004 are ANSI-standardized bulbs recognized in the United States and Canada, meaning replacement lamps conforming to those ANSI designations are expected to meet the same electrical and physical standards as the originals.
The 1004 operates at a dual wattage of 21W and 5W corresponding to its two filaments, whereas the 89 operates at a fixed 13W from its single filament, reflecting a meaningful difference in power draw between the two bulb types used across LeMans model years.