My headlights work just fine, but my tail lights, license plate lights, running lights and dash lights won't work. I've changed the fuses and replaced the illumination relay and the bulbs and they still won't work. I've also checked to make sure the switch on the steering wheel console was off and there seems to be no problem there either. My rear wiper stopped working a while before the lights quit working, and I had to disconnect the rear wiper motor because it was making an awful noise whenever the car was on. Not so concerned about getting the wiper functioning, but thought it may be related somehow. I tried plugging the motor back in and it had no effect on the light situation.
Tail lights, license plate lights, running lights and dash lights won't work on 1999 Subaru Legacy Outback
What I would do is I would check the output of the head light switch that powers up the tail lights etc. Sometimes just 1 part of a switch can fail.