2018 Ford F-350 Super Duty Fuse Box Diagram & Amperage

Quick answer

The 2018 Ford F-350 Super Duty has two main fuse box locations: one in the engine compartment (under the hood) and another inside the cabin (under the dashboard on the passenger side kick panel).

Engine Compartment Fuse Box

This fuse box is located in the engine bay, on the driver's side near the battery. It contains fuses and relays for critical engine functions, lighting, and other high-current accessories.

Note: Fuse locations and amperages can vary slightly depending on your F-350's specific trim level and optional equipment. Always refer to the fuse box diagram printed on the inside of the fuse box cover for the most accurate information for your vehicle.

Passenger Compartment Fuse Box

This fuse box is located behind the kick panel on the passenger side, near the floorboard. It houses fuses for various interior electrical components and accessories.

Note: As with the engine compartment fuse box, refer to the diagram on the fuse box cover for the most accurate information specific to your 2018 Ford F-350 Super Duty.

How to Test a Fuse

Testing a fuse is a straightforward process:

1. Locate the fuse: Identify the suspected fuse using your vehicle's fuse box diagram.
2. Turn off the ignition: Ensure the vehicle is off to prevent electrical shorts.
3. Carefully remove the fuse: Use a fuse puller (usually found in the fuse box or tool kit) or small needle-nose pliers.
4. Visually inspect the fuse: Look at the metal wire inside the fuse. If it's broken or melted, the fuse is blown and needs to be replaced.
5. Use a multimeter (for a more precise test):
   • Set your multimeter to the continuity setting (usually indicated by a sound wave or diode symbol).
   • Touch the probes to the two metal prongs on top of the fuse. If the multimeter beeps or shows a reading close to zero ohms, the fuse is good. If there's no beep or an "OL" (open circuit) reading, the fuse is blown.
6. Replace with a new fuse: If the fuse is blown, replace it with a new fuse of the exact same amperage rating and color. Using a fuse with a higher amperage can lead to serious electrical damage or fire.

Common Blown Fuses on This Vehicle

While any fuse can blow, some are more commonly encountered on the 2018 Ford F-350 Super Duty due to the demands on their circuits:

• Cigar Lighter / 12V Power Outlets (Fuses 3 & 4 in Passenger Compartment Fuse Box): These are frequently blown due to overcurrent from charging multiple devices or using high-power accessories. If your phone charger or dash cam stops working, check these first.
• Trailer Brake Controller (Fuse 11 in Engine Compartment Fuse Box): Given the F-350's towing capabilities, this fuse can blow if there's a short in the trailer's wiring or an excessive load on the trailer brake system. If your trailer brakes aren't working, this is a prime suspect.
• Blower Motor (Fuse 14 in Engine Compartment Fuse Box): The blower motor draws a significant amount of current, especially on higher settings. If your fan only works on certain speeds or not at all, this large fuse is often the culprit.
• Headlight Fuses (Fuses 5-8 in Engine Compartment Fuse Box): While less common with modern sealed-beam units, a short in the wiring or a faulty bulb can still cause these to blow, leading to a loss of a headlight.
• Radio / Infotainment (Fuse 1 in Passenger Compartment Fuse Box): Issues with aftermarket installations or internal shorts within the radio unit itself can sometimes lead to this fuse blowing. If your radio is completely dead, check here.

Always check for the underlying cause of a blown fuse. A fuse blows to protect the circuit from an overload or short circuit. Simply replacing a fuse without addressing the root cause will likely result in the new fuse blowing again.

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