Hmmm... The headlights are always on, so the hi lo beam does always have juice when the key is on. If that were connected to the start button instead, when you turn the key on you would be supplying the start button with power and shorting the circuit at the fuse. It does sound possible that it is just a boo boo on the 2 connections.
You could use the ohms or buzzer of a multimeter to see if the start button connection inside the signal housing is in fact the same wire on the plug side. This would work for the High/Low beam as well(nice easy test). There are very small numbers on the "inside headlight" connector that designate the wires. #1, #3, #6 and #8 are high/low beam and #11 and #12 are start button. I would check the start buttons contacts to the #11 and #12 pins on the plug first, if one doesnt connect you have found the culprit.
Other than that, is you splicing at all inside the bars? If so, I think you know where I'm goin' with that. (Possible shorting together)
