What is the low beam headlight bulb size for a 1978 Mercury Zephyr?

The 1978 Mercury Zephyr uses a H4656 bulb for the low beam headlights. We recommend upgrading to LED for better visibility.

What is the high beam headlight bulb size for a 1978 Mercury Zephyr?

The high beam bulb size for the 1978 Mercury Zephyr is H4651.

Why are my 1978 Mercury Zephyr headlights dim?

Dim headlights on a 1978 Mercury Zephyr can be caused by aging halogen bulbs, which lose brightness over time, or oxidation (cloudiness) on the plastic headlight lenses. Upgrading to a H4656 LED conversion kit can provide a significantly brighter and whiter light output.

Which bulb fits the 1978 Mercury Zephyr fog light?

The 1978 Mercury Zephyr typically does not come with factory fog lights in all trim levels. If your vehicle is equipped with them, check the manual as sizes can vary by trim.

Is the 1978 Mercury Zephyr single or dual beam?

The 1978 Mercury Zephyr uses a dual bulb headlight system. This means you have separate bulbs for high and low beams.

Can I install LED bulbs on my 1978 Mercury Zephyr?

Yes, the 1978 Mercury Zephyr comes with standard halogen bulbs from the factory, but they can be upgraded to LED. You will need a H4656 LED conversion kit for the low beams.

How do I change the headlight on a 1978 Mercury Zephyr?

Turn off the vehicle and open the hood. Locate the headlight assembly from behind, remove the dust cover or retaining clip, disconnect the wiring harness, twist the old H4656 bulb counter-clockwise to remove it, then insert the new bulb and reassemble. The whole process typically takes 10 to 30 minutes per side depending on accessibility.

Are LED headlights legal for a 1978 Mercury Zephyr?

LED bulbs used off-road or in auxiliary lights are legal everywhere. For on-road headlight use, legality varies by state. Many states allow LED retrofits as long as the beam pattern meets DOT standards. For the best legal compliance, choose a DOT-approved H4656 LED kit that is designed as a direct replacement and produces a proper cutoff pattern without excessive glare.

How much does it cost to replace 1978 Mercury Zephyr headlights?

A pair of halogen H4656 bulbs costs $15 to $40, while LED conversion kits run $25 to $60 per pair. If you have a shop do the work, expect an additional $20 to $50 in labor per bulb. Replacing them yourself at home saves the labor cost and usually takes under 30 minutes.

What is the difference between halogen and LED for a 1978 Mercury Zephyr?

Halogen bulbs produce a warm yellow light (around 3200K), last 500 to 1000 hours, and draw more power. LED bulbs emit a brighter white light (5000-6000K), last 25,000+ hours, and use less energy. LED upgrades for the H4656 position are available as direct plug-and-play replacements.

The 1978 Mercury Zephyr has a unique bulb configuration not shared with adjacent model years.

Fitment Guaranteed for 1978 Mercury Zephyr

What Size Bulbs Does a 1978 Mercury Zephyr Use?

Correct headlight, fog light, and tail light bulb sizes. Sourced from OEM catalog data.

Installation Difficulty

Easy (Plug and Play)

Est. Replacement Cost

$15 - $40 (Halogen) / $30+ (LED)

What Lighting System Does the 1978 Mercury Zephyr Have?

Lighting on the 1978 Mercury Zephyr is managed by a total of 12 bulbs, covering everything from primary headlights to signal indicators. It features an extensive lighting system powered by a dual-bulb halogen configuration using separate H4656 low beam and H4651 high beam bulbs for precise light distribution. This model belongs to the early years of the Zephyr's 1978-1983 production span.

Can You Put LED Bulbs in a 1978 Mercury Zephyr?

Upgrading to LED is one of the most effective ways to modernize your Mercury's appearance and safety profile. We recommend starting your upgrade with the H4656 low beams, as they see the most use. Adding a matching H4651 LED kit later will complete the look and ensure consistent lighting performance.

1978 Mercury Zephyr Bulb Size Chart

Position	Bulb Size	Shop
High Beam	H4651	Buy H4651 →
Low Beam	H4656	Buy H4656 →
Side Marker	194	Buy 194 →
Turn Signal Front	1157A	Buy 1157A →
License Plate	168	Buy 168 →
Brake Light	1157	Buy 1157 →
Turn Signal Rear	1157	Buy 1157 →
Tail Light	1157	Buy 1157 →
Parking Light	1157A	Buy 1157A →
Reverse Light	1156	Buy 1156 →
Dome Light	906	Buy 906 →
Map Light	906	Buy 906 →

How do the 1978 Mercury Zephyr's bulbs compare to other years?

The 1979 model switched to a different bulb configuration.

This bulb configuration covers the 1978 model years. 1979 →

Finding the best installation guide...

Other Zephyr Years

1983 1980 1979

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