2021 Ford F-350 Super Duty Fuse Box Diagram & Amperage
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Quick answer
Your 2021 Ford F-350 Super Duty has two main fuse boxes:
- Passenger compartment fuse panel: Located in the front passenger footwell, behind a trim panel.
- Power distribution box: Located in the engine compartment on the driver's side.
Passenger Compartment Fuse Panel
The passenger compartment fuse panel is located on the right-hand side of the passenger footwell, behind a trim panel. To access it, you may need to remove the kick panel.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| 2 | 10A | Red | Right high-beam headlamp |
| 3 | 10A | Red | Left high-beam headlamp |
| 5 | 15A | Blue | Steering wheel controls, SYNC module |
| 10 | 20A | Yellow | Power outlet #1 (instrument panel) |
| 11 | 20A | Yellow | Power outlet #2 (center console) |
| 12 | 20A | Yellow | Cigar lighter |
| 13 | 10A | Red | Airbag module |
| 19 | 10A | Red | Instrument cluster, Heads-up display |
| 22 | 10A | Red | Ignition switch, Push-button start |
| 23 | 15A | Blue | Fuel pump relay |
| 29 | 30A | Green | Blower motor |
| 32 | 15A | Blue | Brake on/off switch |
| 33 | 15A | Blue | A/C clutch |
| 34 | 10A | Red | Radio/Infotainment system |
| 36 | 15A | Blue | Right low-beam headlamp |
| 37 | 15A | Blue | Left low-beam headlamp |
Relays
- R2: Blower motor relay
- R5: A/C clutch relay
Power Distribution Box
The power distribution box is located in the engine compartment on the driver's side, near the battery.
| Fuse # | Amp | Color | Circuit / Component Protected |
|---|---|---|---|
| 13 | 20A | Yellow | Fuel pump |
| 15 | 30A | Green | Starter motor relay |
| 22 | 60A | Yellow | Anti-lock Brake System (ABS) module |
| 24 | 40A | Green | Ignition switch |
| 33 | 25A | Natural | PCM (Powertrain Control Module) |
| 35 | 25A | Natural | Tail lights, Park lights |
| 45 | 30A | Green | Trailer brake control module |
| 46 | 30A | Green | Trailer tow battery charge |
| 48 | 25A | Natural | Upfitter switch #1 |
| 49 | 25A | Natural | Upfitter switch #2 |
| 50 | 25A | Natural | Upfitter switch #3 |
| 51 | 25A | Natural | Upfitter switch #4 |
| 52 | 40A | Green | Upfitter switches #5 & #6 |
Relays
- R6: Starter relay
- R8: Fuel pump relay
- R10: PCM relay
How to test a fuse
- Turn off the ignition and all accessories.
- Locate the fuse box and remove the cover.
- Identify the suspect fuse.
- Carefully remove the fuse using a fuse puller (often found in the fuse box lid).
- Visually inspect the fuse. A good fuse has an unbroken filament. A blown fuse will have a broken or melted filament.
- If you can't see the filament, you can test it with a multimeter. Set the multimeter to the continuity setting. Touch the probes to each of the fuse's metal tabs. If the multimeter beeps or shows a reading of zero, the fuse is good. If it doesn't, the fuse is blown.
Common blown fuses on this vehicle
- Power outlets/cigar lighter (Fuse #10, #11, #12 in the passenger compartment): These fuses often blow due to faulty phone chargers or other devices plugged into the outlets.
- Trailer lights (Fuse #45, #46 in the power distribution box): Issues with trailer wiring are the most common cause of these fuses blowing. Check for corroded or damaged wiring on the trailer side.
- Fuel pump (Fuse #23 in the passenger compartment and #13 in the power distribution box): If your truck cranks but won't start, a blown fuel pump fuse is a likely culprit.
Note: Fuse numbers and circuits can vary depending on your vehicle's trim level and options. Always consult your owner's manual or the diagram on the fuse box lid to verify the correct fuse for the circuit in question.
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Before you pull a fuse on the 2021 Ford F-350 Super Duty
- Use the label printed on the panel cover or the owner's manual for your exact build. Layouts change with options, model year and build date, so a chart for another truck can be wrong.
- Replace a blown fuse only with the same amp rating. A larger fuse can let wiring overheat.
- A fuse that blows again right away means a short or failing component downstream. Find the cause before replacing it again.
- A good fuse doesn't prove the circuit works — relays, grounds and connectors fail too.
- Disconnect the battery before working near high-current fuses or cables.
Learn more: How fuses, relays and truck electrical systems work
More specs for the 2021 Ford F-350 Super Duty
Oil Capacity & Filter
Capacity, weight, filter PN, drain plug torque, change interval.
Fluid Type Specs
Engine oil, coolant, ATF, diff, brake, PS, DEF — with OEM spec numbers.
Coolant Capacity & Type
Total system capacity, OEM coolant spec, flush interval, bleed tips.
Transmission Fluid & Service
Trans model, fluid spec, capacity, filter PN, service interval.
Torque Specifications
Lug nuts, drain plug, caliper, axle nut, plug, key fasteners.
Brake Pad & Rotor Specs
Pad PNs, rotor size, min thickness, caliper torque.
Tire Size & Pressure
OEM size, cold psi, bolt pattern, wheel size, TPMS.
Battery Size & Group
Group size, CCA, AGM/flooded, dimensions, reset note.
A/C Refrigerant & Oil
R-134a or R-1234yf, charge oz, PAG oil spec.
Bulb Sizes (Headlight, Tail, Fog)
Headlight, fog, tail, turn, reverse, interior.
Factory Maintenance Schedule
Service intervals by mileage, severe-duty notes, known issues.
Towing Capacity & Payload
Max tow, payload, GVWR/GCWR, hitch class by trim.
Serpentine Belt Routing & Length
Belt routing, length, rib count, OEM + aftermarket PNs.
Wheel Alignment Specifications
Camber, caster, toe ranges (front & rear), adjustability notes.
Paint Color Codes
All factory colors with paint codes, sticker location, touch-up tips.
Wiper Blade Sizes
Driver/passenger/rear blade size, attachment, OEM + cross-refs.
Spark Plug Type & Gap
Plug PN, gap, torque, interval by engine.
Transmission & Axle Gear Ratios
Trans gear ratios, axle ratios, RPO codes, tow vs MPG impact.
Key Fob Programming
DIY programming steps, FCC ID, fob PN, battery, transponder.
Same spec — other model years
2000 F-350 Super Duty
2001 F-350 Super Duty
2002 F-350 Super Duty
2003 F-350 Super Duty
2004 F-350 Super Duty
2005 F-350 Super Duty
Maintenance & repair guides
2021 Ford F-350 Super Duty Maintenance Schedule →
Available maintenance guidance; confirm the manufacturer schedule.
Repair planning references →
Plan the scope of work; detailed procedures need configuration-matched evidence.
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Values can vary by engine, trim and build date; check your VIN-specific service information. Updated 2026-07-13.