Mercury Zephyr Dome Light Bulb Size

The Mercury Zephyr dome light uses bulb size 906 and bulb size 912 for interior illumination. Data for the specified lighting components covers the range from 1978 to 1983.

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
1983	906
1982	912
1978-1981	906

Bulb Specifications

Description	Bulb Size
ANSI standard (US & Canada). Miniature wedge bulb (T10). 12V, 8W.	906
ANSI standard (US & Canada). Wedge bulb (T15). Variant of 921. 12V, 12W.	912

Other Locations

Additional Notes

The 906 bulb is the dominant dome light specification for the Mercury Zephyr, covering the 1978-1981 and 1983 model years.
The 906 is an ANSI-standard miniature wedge bulb rated at 12 volts and 8 watts, classified under the T10 form factor.
The 1982 Mercury Zephyr is the sole model year in these specifications to use the 912 bulb for the dome light.
The 912 is an ANSI-standard wedge bulb rated at 12 volts and 12 watts, classified under the T15 form factor, and draws notably more power than the 906.
The 912 is a variant of the 921 bulb, meaning the two share a close relationship in design, though they are not confirmed as interchangeable within these specifications.
The T10 and T15 designations refer to the outer envelope width of the bulb, expressed in eighths of an inch, placing the 912 physically larger than the 906.
Despite both bulbs operating at 12 volts, the wattage difference between the 906 and 912 means they are not electrically equivalent and should not be treated as substitutes for one another.
Both the 906 and 912 use a wedge-style base, which relies on the glass envelope itself to make contact with the socket rather than a separate metal base pin.