I had the same problem on my 94 Blazer and someone here told me to change the brake switch because the brake lights stayed on when I was out of the truck. I went to the local auto store and for 10 bucks that fixed it. There is a metal clip that has to be popped off the break pedal where the switch connects. Once you pop that clip off with a screw driver the switch can be unplugged. I uses my wifes makeup mirro and a flashlight to see under the dash since the steering colum blocked my view. 5 minute repair to do everything with the light and mirror.