Isuzu I-Mark Headlight Bulb Size

The Isuzu I-Mark high beam and low beam headlight bulbs use 9004 or H6054 size bulbs for optimal illumination. The replacement chart covers 1981 to 1989 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
1987-1989	9004	HB1	Check Price
1981-1986	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
1987-1989	9004	HB1	Check Price
1981-1986	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 Isuzu I-Mark uses two distinct headlight technologies across its model years, with the H6054 sealed beam unit fitted to 1981-1986 models and the 9004 halogen bulb fitted to 1987-1989 models.
The 9004 is a dual-filament halogen bulb operating at 12V with a high beam draw of 65W and a low beam draw of 45W, using a P29t base. A single bulb serves both the high beam and low beam functions on 1987-1989 I-Mark models.
The H6054 is a 5x7-inch rectangular sealed beam unit rated at 12V. Unlike a conventional replaceable bulb, the entire H6054 assembly constitutes the light source, meaning the whole unit requires replacement when the light fails.
Both the 9004 and H6054 are ANSI-standardized types recognized in the United States and Canada, meaning fitment follows a defined physical and electrical standard rather than a proprietary specification.
On 1981-1986 I-Mark models, the high beam and low beam headlight positions both use the H6054 sealed beam unit, indicating that separate sealed beam assemblies handle each function rather than a single dual-filament unit.
The transition from the H6054 sealed beam to the 9004 halogen bulb between the 1986 and 1987 I-Mark represents a change in the fundamental headlight construction, as the sealed beam integrates the lens, reflector, and filament into one unit, while the 9004 is a discrete replaceable bulb housed within a separate reflector assembly.
The P29t base of the 9004 bulb is a specific bayonet-style connector, and substituting a bulb with a different base type would be physically incompatible with the 1987-1989 I-Mark headlight socket.