Hummer H2 Map Light Bulb Size

The Hummer H2 map light utilizes 212-2, 578, and 168 bulb sizes for the interior lighting components. Available data for the specified vehicle covers the range from 2003 to 2009.

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
2008-2009	212-2
2008-2009	578 (Rear)
2007	578 (2nd Row, Rear)
2007	168 (Front)
2005-2006	578
2003-2004	578 (2nd Row, Rear)
2003-2004	168 (Front)

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Festoon bulb, 41mm length, SV8.5 base. 12V, 12W.	212-2
ANSI standard (US & Canada). Festoon bulb, 41mm length, end-cap contacts. 12V, 12W.	578
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 4.9W.	168

Other Locations

Additional Notes

The 578 bulb is the most frequently specified map light bulb across the Hummer H2 model range, appearing in positions including the rear, 2nd row, and general map light applications across the 2003-2009 model years.
The 578 is a festoon-type bulb with a 41mm length, operating at 12V and 12W, and uses end-cap contacts rather than a keyed base for electrical connection.
The 212-2 is also a festoon-type bulb with a 41mm length and the same 12V, 12W rating as the 578, but it uses an SV8.5 base rather than end-cap contacts, making the two bulbs physically non-interchangeable despite their identical voltage and wattage ratings.
The Hummer H2 (2008-2009) specifies both the 212-2 and the 578 simultaneously, with the 578 designated for the rear position, indicating that different map light positions within the same vehicle require different bulb types.
The 168 is a miniature wedge bulb of the T10 form factor, rated at 12V and 4.9W, which is significantly lower in wattage than either festoon type specified elsewhere in the H2 lineup.
The 168 bulb is specified exclusively for the front map light position on the 2003, 2004, and 2007 H2, while the 578 handles the 2nd row and rear positions in those same years.
All three bulb types, the 212-2, 578, and 168, conform to ANSI standards applicable in both the United States and Canada.
The 2005 and 2006 H2 specify only the 578 with no positional qualifier, whereas the 2003, 2004, and 2007 models carry position-specific designations, reflecting a difference in how fitment data is recorded across those years.
Because the 212-2 and 578 share the same length and power ratings but differ in base type, substituting one for the other would require a compatible socket, and the physical base difference is the critical factor in determining interchangeability.
The T10 wedge format of the 168 is mechanically distinct from both festoon types, and it is not interchangeable with either the 212-2 or the 578 regardless of the wattage difference.