Headlight

Note the diagram. You can the three fuses, one goes hot with key on, the other two are hot all the time. Did you check for voltages at the fuses? Use a testlight. In the diagram at headlamp, top wire is voltage, bottom wire is ground, need both. You see hi and lo beam relays, It might be possible to pull relay and use jumper wire between the two terminals on the switch of relay, right side in diagram, to see if lamps operate. If they do, then problem on control side of relay, left side in diagram. The control side needs voltage and ground to energize relay. Your dimmer switch grounds control side of relay. I can only help with testing.