brake lights on a 98 ck

hi when i apply the brake pedel lightly the brake lights come on when i apply them more like coming to a stop they dont come on apply fully (hard) they come on any help would be great thanks

sounds like brake light switch out of adjustment/faulty.

Can you duplicate the issue in the driveway in park? If so does the 3rd brake light respond the same as the L & R stop lights?