I have the same issue, but only my headlight is not working. All of my other lights work. My hi/low beam switch doesn't work at all. If you put it in high beam, the high beam indicator doesn't even turn on. But I just installed these bars last night, so right now my bike is unrideable. I hope it is as simple as a fuse, but with operable turn signals, and brake lights, I think I would have to rule that out for now and dig deeper for some pinched wiring on my left hand controls.

According to the diagram the left hand control is wired with the head light and the right hand control keeps them constantly turned on with the turn signals.

correct me if I am wrong.