dash lights keep popping fuse.

when i put a new fuse in and i turn on the head lights the dash light fuse pops. then i turn on the dome light and the dash lights come on but only when the dome light is on. if the fuse to the dashlights is blown why would the dash lights come on when u turn on the dome light?
 
i would check i wiring diagram and see what the two circuits have in common. then start from there. or just put a jumper wire in the fuse and start seeing where smoke comes out. i dont recomend that method though.