Like most vehicles, the 2001 Ford Focus uses a fuse to control power to the headlights (one fuse per bulb). If one of the headlight fuses is burnt out, your headlights will be inoperative. Replacing a bad headlight fuse does not require a trip to the dealer or a service centre; it can be replaced at home, even if you are inexperienced in auto repair. The headlights use typical 10A fuses; you can purchase a package of them at any automotive parts store.
Turn the engine off, open the bonnet, and disconnect the negative battery cable (--) with your pliers.
Locate the power distribution box against the firewall on the driver's side of the engine compartment. Flip up the latch and remove the plastic cover.
Determine which headlight fuse you want to replace. The 2001 Ford Focus uses four headlight fuses--one for each headlight. Fuse number 16 is for the passenger side low beam; fuse number 17 is for the driver's side low beam. Fuse number 26 is for the passenger side high beam; fuse number 27 is for the driver's side high beam.
Grasp the fuse with your fingers and pull it straight out of its mount. Insert the new fuse in its place. Replace the plastic cover and reconnect the negative battery cable.
Inspect the fuse before replacing it to determine if it is the cause of your problem. A bad fuse is identified by its internal wire (visible through the fuse). If the wire is broken or disconnected, the fuse is bad. If it's not, the fuse is fine. If your headlights are not working and the fuse is good, you may have a burnt out headlight bulb or a wiring problem.