which one under dash or engine bay:augie never heard of a fuse box going on a Terrano:nenau now if it was a MK5-7 escort I would understand as it was very common & had to replace mine:doh
Had problems with Central locking not working and indicators searched for days for problems looked at fuse box and then noticed when tipped on its side water came out well horrible browny water. All the connections ports are blue with gunk.
Ouch TBH i'd find out where the water is coming in first & fix the leak:thumbs you might be able to clean up the contacts but it'll need removing from the motor & dried out aswell