These are all excellent responses, but I'm also going to add that my bike was doing the same thing and I found a few other things. First, the plunger in the front master cylinder was all gummed up, not allowing the plunger to push the little tab on the lever far enough out to disengage the brake light switch. You might want to check that out too. Also, the connectors on my Tri-Bar LED tail light were completely dry of grease and every time I got caught in the rain, my brake light would stay on because the water was completing the circuit. I tore apart the tail light, cleaned it up real good, put dielectric grease in the connectors, and have never had that problem again. Hope this helps.

 

Think i might have this "little tab" issue after reassembling when i changed out the handlebars. Anybody have a pics as to what im looking for? Bike is a 2002 deuce. Thanks!

 

Pull your lever, it's right behind it. Push it in by hand and see if the light goes off. Use the little screw repair or replace it. It's not a novice replacement.