Why is my Ford Focus ambient lighting not working?

The most common reason that the ambient lighting will fail to work in the Ford Focus is an accidental adjustment of the brightness knob. The car illuminates Your ambient lighting based on what Your dimmer is set to, so more often than not if it's failing to work as expected, it's because the knob is maladjusted. However, if this doesn't seem to be Your issue, You may have dashboard lights out. Depending on Your model year, Your Focus may use different bulbs. However, it's highly unlikely that all of them have failed at once, so You may be looking for a blown fuse or other circuit interruption. Be sure to check Your dimmer settings first, but then You can move on to more advanced diagnostics.