AM General Hummer Map Light Bulb Size

The AM General Hummer map light utilizes bulb sizes 89 and 912 for illumination purposes within the interior cabin area. Data for the specific components covers the range from 1992 through 2001.

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
1999-2001	912
1992-1998	89

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Wedge bulb (T15). Variant of 921. 12V, 12W.	912
ANSI standard (US & Canada). Single-filament bulb with BA15s bayonet base. Lower wattage variant of 1156. 12V, 13W.	89

Other Locations

Additional Notes

The AM General Hummer uses two distinct map light bulb types across its production run: the 912 for model years 1999-2001 and the 89 for model years 1992-1998.
Both the 912 and 89 bulbs are ANSI-standardized components rated for use in the US and Canada, operating at 12 volts.
The 912 is a T15 wedge-type bulb, meaning it connects by pressing directly into a wedge socket without a separate base or locking mechanism.
The 89 uses a BA15s bayonet base, a single-pin mount that requires a quarter-turn to lock into its socket, making it physically incompatible with the wedge socket used by the 912.
The 912 is rated at 12 watts, while the 89 is rated at 13 watts, placing both bulbs in a low-wattage category consistent with interior lighting applications.
The 912 is a variant of the 921 bulb. While the two share the same T15 wedge form factor, they differ in wattage, so substitution between them affects power draw.
The 89 is a lower-wattage variant of the 1156 bulb. Both share the BA15s bayonet base, but the 1156 operates at a significantly higher wattage, making it a non-equivalent substitute in this application.
The socket type change between the 1998 and 1999 model years reflects a hardware-level difference, as the bayonet base of the 89 and the wedge base of the 912 are not interchangeable.