The lights are supposed to be on in 'P'. In 'lock' they are off. I guess if you are parked on the side of the road and had to leave your bike..... lights are on in 'P' so it doesn't get hit by a car. The 'P' position on the ignition switch powers the rear lights through a separate fuse ( fuse 'B' 10A ). The actual brake light is powered from fuse 'F' 15A which also does the turn signals and the horn. So if neither front or rear brake makes the brake light come on,( and the horn and turn signals work) then look for a bad connector or wire or bulb. I assume the bike runs so you can rule out an ignition switch problem.