Need to check for short on tail light wiring harness on 2004 FLHRS

SOURCE: Short???

not only headlight is energised when the key is turned on,so it could be anything on the switch,dont just replace it over and over,your wire harness will continue to acrue damage. Check for fuse purpose, then look at that circuit for damage
Tail light may be blown or be grounding out.(may be the problem)

SOURCE: 2010 haritage softail clasic -

that panel you are talking about is held on by a 1/2 inch nut right in the middle. and if you remove the seat, you should see a small torx screw around where the **** area is. Once you remove the panel, you will see where the fuel pump is and there will be a connector and a blled off, you can disconnect these. Although the are only power to the pump, you have to disconnect it to remove the tank. Make sure you disconnect the fuel level gauge. and the fuel interconnect. Did you say that when you unplugged the rear connector, you stopped blowing fuses?? This would mean your short is somewhere in that harness. Look under the rear fender for exposed wires, is your tail light after market?? if so look for grounding on the unit, make sure all connectors are connected and no loose wires. If your looking for short on the ignition, remember the ampres given by the ignition system is so great, it will blow your Maxi fuse, so I would pull out a wiring diagram and trace all wires to and from that connector in the rear to the fuse block. Hope this helps, electrical issues are always difficult to diag, over the internet lol Doc

SOURCE: What? A 2004 Dyna Wide

Check the bulb, If its a dual filiment than it would make sense both would be out. Otherwise im at a loss to. usually if that happens ive seen the fuse blow, but, usually your headlight would be out too.

SOURCE: I'm replacing a tail light assembly and wiring

Usually it connects under the seat somewhere and the wires run under the fender in a trough.

good luck
Steve