Isuzu Impulse Headlight Bulb Size

The Isuzu Impulse high beam headlight bulb sizes include H5001, H4701, and H4651, while low beam headlight bulb sizes consist of H5006, H4703, and H4656 across multiple generations. The replacement chart covers 1983 to 1992 production years with corresponding bulb size specifications for each model generation.

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

High Beam Headlight

Years	Bulb Type	Shop
1990-1992	H5001	Check Price
1988-1989	H4701	Check Price
1983-1987	H4651	Check Price

Low Beam Headlight

Years	Bulb Type	Shop
1990-1992	H5006	Check Price
1988-1989	H4703	Check Price
1984-1987	H4656	Check Price
1983	H4652	Check Price

Bulb Specifications

Description	Type	Shop
ANSI standard (US & Canada). 4-inch square sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H5001	Check Price
ANSI standard (US & Canada). 7-inch round sealed beam unit, variant. Not a replaceable bulb — the entire unit is replaced. 12V.	H4701	Check Price
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4651	Check Price
ANSI standard (US & Canada). 5.75-inch round sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H5006	Check Price
ANSI standard (US & Canada). 7-inch round sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4703	Check Price
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4656	Check Price
ANSI standard (US & Canada). 4x6-inch rectangular sealed beam unit, variant of H4651. Not a replaceable bulb — the entire unit is replaced. 12V.	H4652	Check Price

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Additional Notes

All headlight bulb sizes listed for the Isuzu Impulse across both high beam and low beam positions are sealed beam units, meaning the entire lens-reflector-filament assembly is replaced as one piece rather than swapping an internal bulb.
Every sealed beam type specified for the Impulse operates at 12V and conforms to ANSI standards recognized in both the United States and Canada.
The 1990-1992 Impulse uses the H5001 for high beam, a 4-inch square sealed beam unit, paired with the H5006 for low beam, a 5.75-inch round sealed beam unit. These two units are not interchangeable with each other due to their differing shapes and sizes.
The 1988-1989 Impulse uses the H4701 for high beam and the H4703 for low beam. Both are 7-inch round sealed beam units but are distinct variants; the H4701 is noted as a variant of the standard H4703 form, and the two are not listed as interchangeable.
The 1983-1987 Impulse relies on 4x6-inch rectangular sealed beam units across both beam positions. The high beam position uses the H4651 throughout all five of those years, while the low beam position uses the H4656 for 1984-1987 and the H4652 for 1983.
The H4652, fitted to the 1983 low beam position, is a variant of the H4651 used in the high beam position. Despite sharing the same 4x6-inch rectangular format, they are listed as separate part numbers and are not specified as direct substitutes for one another.
The headlight configuration of the Impulse changed three times across its production span, shifting from 4x6-inch rectangular sealed beams, to 7-inch round sealed beams, and finally to a mixed format pairing a 4-inch square high beam with a 5.75-inch round low beam.
Because each sealed beam format is physically distinct in shape and size, units from one generation of the Impulse are not compatible with mounting positions from another generation without modification to the housing.