2021 Ford F-150 — Bulb Sizes (Headlight, Tail, Fog)

Quick reference

Notes:

• 2021 F-150 introduced widespread factory LED lighting. XL/XLT commonly have halogen headlamps/fogs unless optioned. Lariat/King Ranch/Platinum/Limited typically include LED headlamps, LED fogs, and LED tail lamps (sealed, no serviceable bulbs).
• Sizes listed are the most common for incandescent-equipped 2021 F-150s; always verify by VIN or visual inspection, as mid-year or package changes can vary.

LED vs halogen upgrade considerations

• CANBUS/load detection: The 2021 F-150 monitors exterior bulbs. Swapping incandescent 7443/7444NA/921/194 to LEDs can trigger bulb-out messages or hyperflash. Use CANBUS-ready LEDs or add load resistors (commonly 6Ω, 50W per turn-signal circuit) mounted to metal away from wiring.
• DRL/high-beam behavior: On halogen trucks, the 9005 high beam often runs as a DRL via PWM at reduced voltage. Choose LED 9005 bulbs that are DRL/PWM compatible or include an anti-flicker module to avoid strobing.
• Headlamp housings: LED replacement bulbs in halogen reflector housings can create glare if the emitters don’t mimic filament position. Aim for quality LEDs with adjustable orientation and ensure proper aim after installation.
• Fog lights: If you have LED fog modules from the factory, they’re sealed; you’ll replace the assembly, not a bulb. For halogen H10/9145 fogs, use compact LEDs that clear the dust cap and are rated for moisture/heat.
• BCM programming: Some owners reconfigure lamp types via dealer tool or aftermarket software; results vary. Load resistors remain the most reliable cure for hyperflash on turn signals.

How to replace each bulb

• Low beam (H11, halogen): Turn the front wheels for access, remove the headlamp access cover behind the housing, twist the H11 counterclockwise, unplug, swap, and reinstall without touching the glass.
• High beam/DRL (9005, halogen): Similar rear access; twist out the 9005, disconnect, and replace. Confirm DRL function without flicker if using LEDs.
• Fog light (H10/9145, halogen): From the wheel well, remove the liner fasteners near the fog area. Twist the bulb out of the fog housing, swap, and test before reassembling. LED fog modules require removing the bezel and three fasteners to change the entire unit.
• Front turn signal (7444NA/3157A): Access from behind the headlamp. Rotate the socket counterclockwise, pull out the bulb, replace with amber-compatible part. Test hazards for hyperflash.
• Front side marker/parking (194): Small wedge bulb in the headlamp’s side socket. Gently pull straight out and push in the new 194.
• Rear brake/tail and turn (7443, incandescent tails): Lower the tailgate, remove the two tail lamp bolts, slide the assembly straight back, rotate the socket, and replace the 7443. This bulb handles tail, brake, and turn on incandescent setups.
• Reverse (921): With the tail lamp out, rotate the reverse socket, swap the 921. Bright LED upgrades improve camera visibility.
• Rear side marker (194): Remove tail lamp, access the side marker socket, swap the 194.
• License plate (194): From under the tailgate lip, pop out the lens, rotate the socket, and replace the 194.
• Interior map (194): Carefully pry the lens, pull the wedge bulb, insert new 194. Use trim tools to avoid marring.
• Dome/cargo (578 festoon): Pry the lens, spring the festoon clips, replace with a 41mm bulb. Observe polarity on LEDs.

Common lighting issues for this generation

• Hyperflash after LED swaps: Caused by low current draw. Use CANBUS LEDs or resistors; verify good grounds at sockets.
• PWM-related flicker: Some aftermarket LEDs (especially 9005 DRL and 921 reverse) flicker due to PWM. Choose PWM-compatible bulbs or add anti-flicker modules.
• Condensation in headlamps/tail lamps: Early assemblies may show temporary fogging. Persistent moisture suggests a compromised vent or seal—replace the housing under warranty or reseal.
• Socket heat and discoloration: Over-wattage bulbs or poor connections can overheat 7443/7444NA sockets. Inspect and replace pigtails if brittle or browned.
• Trailer wiring faults: Corroded 7/4-pin connectors can cause lamp-out warnings. Clean and dielectric-grease the terminals.

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