What is the low beam headlight bulb size for a 1991 Ford F Super Duty?

The 1991 Ford F Super Duty uses a 9004 bulb for the low beam headlights. We recommend upgrading to LED for better visibility.

What is the high beam headlight bulb size for a 1991 Ford F Super Duty?

The high beam bulb size for the 1991 Ford F Super Duty is 194.

Why are my 1991 Ford F Super Duty headlights dim?

Dim headlights on a 1991 Ford F Super Duty can be caused by aging halogen bulbs, which lose brightness over time, or oxidation (cloudiness) on the plastic headlight lenses. Upgrading to a 9004 LED conversion kit can provide a significantly brighter and whiter light output.

Which bulb fits the 1991 Ford F Super Duty fog light?

The 1991 Ford F Super Duty 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 1991 Ford F Super Duty single or dual beam?

The 1991 Ford F Super Duty uses a dual bulb headlight system. This means you have separate bulbs for high and low beams.

Can I install LED bulbs on my 1991 Ford F Super Duty?

Yes, the 1991 Ford F Super Duty comes with standard halogen bulbs from the factory, but they can be upgraded to LED. You will need a 9004 LED conversion kit for the low beams.

Did the 1991 Ford F Super Duty change headlight bulb sizes from the previous year?

Yes — the 1991 Ford F Super Duty uses different bulb sizes than the 1990 model. The 1991 generation introduced this bulb configuration.

Is the 1991 Ford F Super Duty the first or last year to use 9004 bulbs?

The 1991 Ford F Super Duty is the only year in the 1991 generation to use the 9004 bulb for the low beam headlight.

How do I change the headlight on a 1991 Ford F Super Duty?

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 9004 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 1991 Ford F Super Duty?

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 9004 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 1991 Ford F Super Duty headlights?

A pair of halogen 9004 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 1991 Ford F Super Duty?

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 9004 position are available as direct plug-and-play replacements.

The 1991 Ford F Super Duty has a unique bulb configuration not shared with adjacent model years.

Fitment Guaranteed for 1991 Ford F Super Duty

What Size Bulbs Does a 1991 Ford F Super Duty 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 1991 Ford F Super Duty Have?

Lighting on the 1991 Ford F Super Duty is managed by a total of 11 bulbs, covering everything from primary headlights to signal indicators. It features an extensive lighting system powered by a dual-bulb halogen configuration using separate 9004 low beam and 194 high beam bulbs for precise light distribution.

Can You Put LED Bulbs in a 1991 Ford F Super Duty?

For a Ford built for the road and trail, LED upgrades provide the high-contrast lighting needed for better obstacle detection. We recommend starting your upgrade with the 9004 low beams, as they see the most use. Adding a matching 194 LED kit later will complete the look and ensure consistent lighting performance.

1991 Ford F Super Duty Bulb Size Chart

Position	Bulb Size	Shop
Low Beam	9004	Buy 9004 →
Side Marker	3157CK	Buy 3157CK →
Turn Signal Front	3157CK	Buy 3157CK →
Parking Light	3157	Buy 3157 →
Tail Light	3157CK	Buy 3157CK →
Turn Signal Rear	3157	Buy 3157 →
License Plate	194	Buy 194 →
Reverse Light	3156	Buy 3156 →
Brake Light	3157CK	Buy 3157CK →
High Beam	194	Buy 194 →
Dome Light	912	Buy 912 →

How do the 1991 Ford F Super Duty's bulbs compare to other years?

The 1991 Ford F Super Duty changed bulb sizes from 1990. The previous model year used a different configuration.

The 1992 model switched to a different bulb configuration.

This bulb configuration covers the 1991 model years. ← 1990 1992 →

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Other F Super Duty Years

1997 1996 1995 1994 1993 1992 1990 1989 1988

Other Vehicles That Use 9004 Bulbs

2005 Pontiac Montana 2004 Oldsmobile Silhouette 2003 Dodge Ram Van 2003 Dodge Wagon 2002 Mercedes-Benz SL-class 2002 Mercedes-Benz SL500