Mercury Marquis License Plate Bulb Size

The Mercury Marquis license plate light utilizes unique bulb sizes 168, 194, 90, 631, 97, and 1155 depending on the specific version of the vehicle. Available data for the lighting components covers a range from 1967 through 1986.

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
1986	168
1983-1985	194
1980-1982	168
1979	194
1977-1978	168
1975-1976	194
1973-1974	90
1972	631
1968-1971	97
1967	1155

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 4.9W.	168
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 3.78W.	194
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. 12V, 13W.	90
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 21W.	631
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 13W.	97
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Variant of 1156. 12V, 21W.	1155

Other Locations

Additional Notes

The Mercury Marquis license plate bulb specifications span model years 1967 through 1986, covering six distinct bulb types across that range.
The 168 and 194 are the most frequently specified bulbs in this data set, both classified as T10 miniature wedge bulbs operating at 12V under the ANSI standard for the US and Canada.
Although the 168 and 194 share the same T10 wedge form factor, they differ in wattage. The 168 draws 4.9W while the 194 draws 3.78W, meaning the two are not electrically identical despite their physical similarity.
The Mercury Marquis (1980-1982 and 1986) uses the 168 bulb, while the 1983-1985 model years use the 194 bulb, reflecting alternating specifications across closely grouped years.
The 90 bulb, specified for the 1973-1974 Mercury Marquis, uses a BA15s single-contact bayonet base and operates at 12V with a relatively high draw of 13W compared to the wedge-type bulbs used in later years.
The 97 bulb, used across the 1968-1971 model years, also carries a BA15s bayonet base and shares the same 13W rating as the 90 bulb, though the two are distinct ANSI part numbers and are not listed as interchangeable.
The 631 and 1155 bulbs, specified for the 1972 and 1967 model years respectively, both operate at 12V and 21W with a BA15s bayonet base, and both are classified as variants of the 1156 bulb type.
Because the 631 and 1155 are variants of the 1156, physical and electrical compatibility with a standard 1156 may exist, though substitution decisions depend on socket and housing tolerances specific to each model year.
The BA15s bayonet base found on the 90, 97, 631, and 1155 bulbs is a single-contact design, distinguishing it from dual-contact bayonet bases and making cross-substitution between single and dual-contact types incompatible.
The shift from bayonet-base bulbs in the earlier model years to T10 wedge-base bulbs in the later model years reflects a broader industry transition in miniature automotive lighting socket design.