Mercury Topaz License Plate Bulb Size

The Mercury Topaz license plate light requires a 194 or 168 bulb size depending on the specific version of the vehicle. Available data for the lighting components covers the range from 1984 to 1994.

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
1985-1994	194
1984	168

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 3.78W.	194
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 4.9W.	168

Other Locations

Additional Notes

The Mercury Topaz uses the 194 bulb for the license plate position across the 1985-1994 model years, with the sole exception of the 1984 model year, which takes the 168 bulb instead.
Both the 194 and 168 are ANSI-standardized bulbs recognized in the United States and Canada, meaning they conform to a defined set of electrical and physical standards rather than being proprietary fitments.
Both bulbs share the T10 miniature wedge form factor, which refers to a small, wedge-shaped base that seats directly into a socket without a separate metal base or bayonet pins.
Both bulbs operate at 12 volts, consistent with the standard electrical system voltage found in passenger vehicles of this era.
The 194 bulb is rated at 3.78 watts, while the 168 bulb is rated at 4.9 watts, meaning the 168 draws noticeably more current from the circuit despite sharing the same T10 wedge base as the 194.
Because the 194 and 168 share the T10 wedge base, they are physically interchangeable in terms of fitment, but the wattage difference means substituting one for the other places a different electrical load on the socket and wiring.