Dash lights do not work 2000 ford exploier

All go out at once, first check fuses,then dimmer switch for dash lights, finally headlight switch. To check dimmer switch, pull connection off back, on harness with test light and headlight switch activated, 1 of the leads should have power, if so, use ohm meter on dimmer to make sure it has reading between 0 and some value, if no value, open, dimmer is bad, if there wasn't power then check headlight switch, there should be heavier gauge wire that powers switch and 1 for output to hi/lo switch, smaller gauge wires for tail lamps, dash lights, license plate lamps, parking lights. The color wires from dimmer would correspond to the same colored wires on headlamp switch, probe that connection on headlamp switch with switch engaged and see if you have power, if not replace switch, if so, check wire from switch to dimmer.Now if the lights slowly went from bright one day, to less bright some other day, to not working, then the bulbs are bad... good luck...