My fatboy has the ingni relocated down by the starter. When the key is out and the bike is off the lights come back on. i have changed the ingnition once when this happened before any help on what might fix it. it was fine for about a month after bing fixed. i had just washed it and the problem started again. i have washed it prior to this with the new ingnition.

 

Sounds like you're putting a switch on that is allergic to garden hoses. Take it apart and see if it is getting wet inside. Wouldn't want to be riding a bike where the ignition switch shorts out.