Gregorz
Fuse no5 is on ignition circuit, check ignition switch,emergency cut out switch on right handle bar and alarm system if you have one. thats the only places I can see that this fuse feeds.
Could be loose wires inside any of these or some moisture getting in.
I posted a copy of the wiring diagram under "heated wiring grips" on april 2, 2011. I can't post a link as I am on a puter that has got copy + paste blocked.