@Jag - that is a Classic schematic and
@Son_Of_Dog has Touring which is a
little bit different - however your note about how the horn works (grounds the negative side when switch closed) & the brake light not working are well-founded (the difference would be on a classic it would also affect the turns, but not on a Touring)
I think the turns not working (on a Classic) and therefor the brake light (as well as the horn in question) would definitely be noticable to the rider - but on a Touring,brake light function not so much!
@Steel - again good advice regarding using relay - just a minor correction that it's not a
little more current - a Stebel pulls a whopping 18A of current!!! Think about that in these terms - that is like FOUR 55W headlights all wired in parallel! I only stress this because some might be tempted not to use relay if the presumption was it was only a little more. It's absolutely essential to use a relay (along with some decent gauge wire to go with it).