GMC Sonoma Headlight Bulb Size

GMC Sonoma headlight bulbs utilize 9005, H4666, and H6054 sizes for high beam applications, while low beam configurations employ 9006, H4666, and H6054 bulb sizes. A replacement chart covering 1991 through 2004 model years documents the corresponding bulb size specifications for each production year.

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 Size
1998-2004	9005
1994-1997	9005 (With Halogen Capsule Headlamps)
1994-1997	H4666 (With Sealed Beam Headlamps)
1991-1993	H6054

Low Beam Headlight

Years	Bulb Size
1998-2004	9006
1994-1997	9006 (With Halogen Capsule Headlamps)
1994-1997	H4666 (With Sealed Beam Headlamps)
1991-1993	H6054

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Single-filament halogen bulb with P20d base. 12V, 65W.	9005
ANSI standard (US & Canada). Rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H4666
ANSI standard (US & Canada). 5x7-inch rectangular sealed beam unit. Not a replaceable bulb — the entire unit is replaced. 12V.	H6054
ANSI standard (US & Canada). Single-filament halogen bulb with P22d base. 12V, 55W.	9006

Other Locations

Additional Notes

The 9005 and 9006 bulbs are the most frequently specified types across the GMC Sonoma's headlight fitment data, covering high beam and low beam positions respectively for the 1998-2004 model years.
The 9005 is a single-filament halogen bulb rated at 12V and 65W, using a P20d base, while the 9006 is also a single-filament halogen rated at 12V but draws 55W through a P22d base. The two bases are physically distinct, meaning the bulbs are not interchangeable despite their similar construction.
The H4666 and H6054 are sealed beam units rather than replaceable bulbs. When either type fails, the entire headlamp assembly is replaced as a single unit.
The H6054 is a 5x7-inch rectangular sealed beam and was the sole headlight specification for the GMC Sonoma in 1991-1993, covering both high and low beam functions within one unit per side.
For the 1994-1997 model years, the GMC Sonoma carried two distinct headlamp system configurations: vehicles equipped with sealed beam headlamps used the H4666 unit, while those equipped with halogen capsule headlamps used the 9005 for high beam and the 9006 for low beam.
The H4666 sealed beam unit handles both high and low beam output within a single rectangular assembly, which is a structural characteristic shared with the H6054 format.
All four bulb types listed in the specifications conform to ANSI standards applicable in both the United States and Canada, and all operate on a 12V electrical system.
Because the 1994-1997 fitment depends on headlamp system type rather than model year alone, confirming whether a specific vehicle has sealed beam or halogen capsule headlamps is necessary before selecting a replacement bulb.