Rear tail lights on 2002 chevy blazer wont go off

under the dash on the driver side there is a brake switch. It is a switch that when the brake peddle is not engaged it opens the circuit. If that switch fails or gets out of adjustment your brake lights will stay on.

One test is have someone pull up on the bake pedal to see if they go off.
any way you look at it, you need to get under there to fix it. Some times if you remove it, and pull it all the way out and reinstall it, it will reset itself. if that does not work replace it.

Hope this helps .