When i bought my 929 the same thing was happening. Took me and a friend an afternoon to figure it out. But what happened was the guy who had it before me did a 'backyard' removal of the rear turn signals and wired everything up all wrong. And i think out of despiration he just adjusted that switch by the brake pedal so that the brake lights stayed on the entire time. If you adjust that little switch, you should get the brake lights to go off and just the running lights will be on.
Another thing, if you still have the stock brake light, make sure someone didnt replace the bulbs with ones with a single fillament. It should be a dual fillament because one stays on all the time for the running light and the other comes on for the brake (or in my case the turn signal also).