The running board lights on your 1998 Ford Expedition Eddie Bauer are controlled by a relay located in the under-dash fuse panel. To access the fuse panel, you will need to:
1. Open the driver's side door.
2. Locate the fuse panel cover on the left side of the dashboard.
3. Pull the fuse panel cover off to expose the fuses and relays.
4. Locate the relay labeled "Running Board Lights".
5. Remove the relay from the fuse panel.
6. Inspect the relay for damage. If the relay is damaged, replace it with a new relay.
7. Reinstall the relay into the fuse panel.
8. Replace the fuse panel cover.
Note: If the relay is not damaged, there may be a problem with the wiring or the light bulbs. You should have a qualified mechanic diagnose and repair the problem.