Mercury Topaz Headlight Bulb Size

Mercury Topaz headlight bulbs utilize 9004 and H6054 sizes for both high and low beam applications. Replacement chart data spans 1984 to 1994 production years with corresponding bulb size specifications.

The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.

High Beam Headlight

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
1986-1994	9004	HB1	Check Price
1984-1985	H6054	H6054	Check Price

Low Beam Headlight

If US Type and EU Type show the same value, a direct cross-reference for this bulb is not available or the data is insufficient.

Years	US Type	EU Type	Shop
1986-1994	9004	HB1	Check Price
1984-1985	H6054	H6054	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). Dual-filament halogen bulb with P29t base. 12V, 65W/45W.	9004	Check Price
ANSI standard (US & Canada). 5x7-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H6054	Check Price

Other Locations

Additional Notes

The 9004 is a dual-filament halogen bulb, meaning a single unit contains both the high beam and low beam filaments. It operates at 12 volts, with the high beam filament rated at 65 watts and the low beam filament rated at 45 watts. It uses a P29t base and conforms to ANSI standards recognized in the United States and Canada.
The Mercury Topaz used the 9004 bulb for both the high beam and low beam headlight positions across the 1986-1994 model years. Because both positions share the same bulb type, a single 9004 unit serves the full headlight function for those years.
The H6054 is a 5x7-inch rectangular sealed beam unit rather than a replaceable bulb. The entire assembly is the light source, and replacement involves swapping the whole unit. It also operates at 12 volts and conforms to ANSI standards recognized in the United States and Canada.
The Mercury Topaz used the H6054 sealed beam unit for both the high beam and low beam headlight positions in the 1984-1985 model years. As with the 9004 in later years, both positions share the same unit type.
A transition from the H6054 sealed beam unit to the 9004 halogen bulb occurred between the 1985 and 1986 model years. These two bulb types are not interchangeable, as they differ in construction, base type, and installation method.
The 9004 bulb's P29t base is a specific connector type, and substituting a bulb with a different base would require a wiring adapter or socket modification, which falls outside the original factory specification for the 1986-1994 Topaz.