Recently had two different Fiestas come in for safety inspection, both had inop running light issue. Tracked it down to the underhood fuse box. Apparently there isn't a weather seal on the cover and found all the fuses and relays covered in dust and dirt. The fuse for running lights is a 15amp micro fuse that was so badly corroded that when I pulled it out, the leg was broken off and stuck in the pin of the fuse box. Used compressed air, brake cleaner and contact cleaner with a connector cleaning tool. You can replace the micro fuses with mini fuses if you must, they will fit in the box.

Iain McMahon
Technician
Select Auto Service
Windsor, Ontario, Canada