Check the power distribution center under the hood first, as it contains high-amperage links for systems like ABS, starter, and cooling fan. This unit is mounted near the battery and includes labeled slots that correspond to specific circuits.
Match each component by amperage rating and position number, typically ranging from 10A to 50A. Using the wrong rating can damage wiring or connected devices. Inspect the metal strip inside each element for breaks or burn marks before replacing it.
The interior panel, located on the driver side near the dashboard edge, controls lower-current circuits such as lighting, radio, and power outlets. Remove the trim cover to access the panel and use the printed layout for accurate identification.
Relays in the engine compartment manage switching for systems like fuel delivery and ignition. If a system fails intermittently, swap a relay with an identical one in the same unit to test functionality without installing new parts.
Disconnect the negative battery terminal before working on any electrical distribution point to prevent short circuits and protect onboard modules from voltage spikes.
1999 Ford Expedition Fuse Box Diagram with Fuse Locations Relay Layout and Circuits
Use the under-hood power distribution center as the main reference for high-current circuits, since it supplies systems like ABS, starter motor, and cooling fan. Each slot is numbered and mapped to a specific circuit, with ratings typically between 20A and 50A for these components.
Identify slots by both number and amperage marking to avoid incorrect replacements. The layout printed on the cover matches each position to a function such as PCM power, blower motor, or trailer tow circuits.
Engine compartment layout details
Main relay units are grouped in one section of the power center and control switching for ignition, fuel pump, and cooling systems. If a component fails intermittently, swapping identical relay units within this panel can help confirm the issue.
The interior panel manages lower-current circuits tied to cabin features, including radio, interior lights, and power windows. Ratings in this section usually range from 10A to 25A, and each slot is labeled for quick identification.
Common circuit assignments
- 20A slots for ignition and control modules
- 30A–40A slots for blower motor and power accessories
- Relays for fuel pump and starter engagement
Check for visible damage such as melted plastic or darkened terminals, as heat buildup often indicates poor contact or overload conditions.
Secure each component firmly after inspection, since loose connections can cause intermittent electrical faults without fully interrupting the circuit.
Where Fuse Boxes Are Located in 1999 Ford Expedition and How to Access Them
Open the hood and locate the main power distribution center near the battery on the driver side, as this unit contains high-amperage links and relays for major systems. Release the retaining clips on the cover and lift it upward to access the internal layout; the underside of the lid shows slot numbers and circuit assignments for quick reference.
The interior panel is positioned on the driver side of the dashboard behind a removable trim cover. Pull the cover outward from its edge to expose the panel, which handles lower-current circuits such as lighting, radio, and power accessories. Disconnect the negative battery terminal before opening either panel, and use a puller tool to remove components without damaging contacts.