No headlight or tail light - 2000 Harley Davidson XL Sportster 883

Had a 1988 s10 with the opposite problem. Had taillights but no headlights. Turns out that only part of the headlight switch had gone out. It allowed the tail lights and all other lights to work but not the headlights. replacing the headlight switch fixed the problem. Perhaps the switch on yours has went out just on the opposite side that mine did. That switch operates both head and tail lights. Check for power at the tail lights. If there is no power there, check that all the fuses are good. Replace any you find that are blown. If you still have no power, replace the headlight switch. If there is power at the tail lights, clean or replace the bulb sockets.

All of the marker and tail lights are powered from a 15amp fuse going thru the headlight switch on a brown wire. Do you have power from that circuit coming out of the headlight switch ?

Headlight switch is worn out, had the same thing on an old Ford pickup truck.

Could be the headlight switch.
The switch has two sets of contacts for the parking lights, the park position and headlight position.
You may need to check the circuit at the switch to see if you are loosing power when the switch is moved from park to head.

No. Dash lights being out could be a bad headlight switch, since the dash lights are routed through the headlight switch, not the dimmer switch. Park and tail lights also controlled by the headlight switch.

tail lights and dash lights should be on th same fuse and sounds like u have a bad headlight bulb also 2 problems!

I had this very same problem on a GM truck at work the other day, I believe it to be a bad headlight switch because I cycled the switch between headlight and parking light positions, I had tails when I had the switch in the parking light position and not in the headlight position, changed the switch and everything worked, Made my day!

If the tail lights and the dash lights stopped working and the tail light and the panel lighting fuses are both o.k. and you can find no other blown fuses then the problem is most likely the headlight switch.

The relay has nothing to do with the tail lights, but replacing the switch sounds like a good idea. There's a nut holding it in place, see http://www.skandix.de/en/spare-parts/electrics/switches/switch-headlight/1027524/ to get an idea of the construction. And the price. This is not worth fiddling about unreliable workarounds...
In addition, if fuses 15 and/or 16 burn frequently there might be a problem with the tail light cabling.

Good luck
Ingo

look for the relay for the parking light