I cannot explain it! Yellow/black horn wire comes from left handlebar switch, but it goes into wrong hole and that is why horn didn't work! So y/black horn wires didn't contact each other because one of them was in wrong hole.
Fleet mechanic messed up connector?
I installed jumper wire.

 

You are giving me a headache.

 

Don't worry about it, headaches are normal for meat eaters. And high blood pressure too.