Locate the main power distribution unit in the engine compartment near the battery, as most high-current issues originate from this area.
This unit contains large blade inserts and relays controlling systems such as cooling fans, ignition, and charging. Each slot is marked with a number and amperage rating, often ranging from 20A to 60A depending on load.
Check the printed scheme on the cover to match each position with its circuit. This layout helps identify connections for engine control, lighting, and accessory systems, allowing precise troubleshooting.
Remove inserts using a puller tool and inspect the internal metal strip. A break or discoloration indicates failure. Install only the same amperage rating to prevent wiring damage.
Disconnect the negative battery terminal before working with electrical components to reduce the risk of short circuits and protect onboard modules.
2017 E450 Fuse Box Diagram and Layout Guide
Check the power distribution unit near the battery first and match each slot with its assigned amperage printed on the cover to avoid installing the wrong element.
The layout inside the engine compartment is divided into grouped circuits, with high-current links placed closer to the battery feed and lower-rated positions arranged along the outer rows. Each slot is labeled with a number and function code, which corresponds to systems such as ignition, lighting, cooling fans, and control modules.
To read the layout correctly, align the cover legend with the physical arrangement and verify orientation before pulling any component. Misalignment can lead to selecting the wrong slot, especially in tightly packed rows.
- Main relay circuits are located near the center
- Cooling fan protection sits in higher amp positions
- Lighting circuits are grouped along one edge
- Control modules use smaller rated elements
Use a puller tool stored in the compartment to remove components without damaging contacts. After removal, inspect the metal strip inside each piece; a break indicates failure and requires replacement with the same rating.
When reinstalling, press each element firmly into place until it seats fully. Loose contact points can lead to intermittent electrical faults that mimic larger system issues.
Keep a printed reference of the layout in the glove compartment for quick checks during roadside troubleshooting, especially when dealing with sudden electrical loss.
Fuse box locations in 2017 E450 cabin and engine compartment
Open the passenger side dash panel first and remove the trim cover to access the interior electrical center where low-amperage circuits for lighting, infotainment, and auxiliary systems are grouped.
This cabin-mounted unit sits behind a snap-in panel near the glove area, positioned for quick reach without tools. Each slot is arranged in vertical rows, with labeling printed on the inner side of the cover. Use this reference to match circuit numbers before pulling any component.
Cabin access details
To reach the interior block:
- Turn off ignition and all accessories
- Pull the trim panel gently from the edge
- Locate the plastic puller clipped inside
- Identify the correct slot using the legend
Move to the engine compartment for high-current protection elements, located next to the battery on the driver side. This power distribution center is enclosed in a sealed plastic housing with a locking lid designed to protect against moisture and debris.
Engine compartment access steps
Release the side tabs and lift the cover upward to expose the internal layout. Larger rated components for starter, cooling system, and charging circuits are grouped near the main feed line, while relays are positioned along the outer section for quick replacement.
Always verify amperage markings before replacement and ensure each component is fully seated after installation. Loose connections in either location can lead to intermittent power loss or system faults.