Mercury Zephyr front and rear side marker bulbs use a 194 bulb size across all configurations. The replacement chart covers 1978 to 1983 production years with corresponding bulb size specifications.
The year-by-year compatibility chart below provides a quick reference to verify the correct bulb size for your vehicle.
The Mercury Zephyr uses the 194 bulb for both front and rear side marker positions across the 1978-1983 model years.
The 194 is classified as a miniature wedge bulb, designated T10 in the international bulb sizing system, where "T" refers to the tubular shape and "10" indicates the width in eighths of an inch.
The 194 bulb operates at 12 volts with a power draw of 3.78 watts, placing it in the low-wattage range typical of marker and courtesy lighting applications.
The wedge base design of the 194 bulb means it is held in its socket by the tension of the base contacts rather than by a bayonet or screw mechanism, which is a common trait in side marker applications of this era.
The 194 bulb carries ANSI standardization recognized in both the United States and Canada, meaning the specification conforms to a defined performance and dimensional standard rather than a proprietary one.
Because the Mercury Zephyr (1978-1983) uses the same 194 bulb size in all four side marker positions, front and rear sockets accept the same replacement bulb without distinction.
The T10 wedge format of the 194 is widely shared across many vehicle makes and model years, which contributes to broad retail availability of this bulb type.
At 3.78 watts on a 12-volt circuit, the 194 draws approximately 0.315 amperes, consistent with the low current demands expected of side marker lighting in passenger vehicles of this period.