Possibly a fuse has blown, or a cable has become disconnected from the switch, or the switch itself has failed. I had a problem like this one, on a 1975 Chev Truck, turns out it was the wire loom connector, which is attached to the underside of the steering column housing, check it to see if the male and female ends are defective, or just loose. Also, use a 12 volt circuit tester to make sure you are getting "Juice" at the brake light switch.
Ring counter A ring counter is a shift register (a cascade connection of flip-flops) with the output of the last one connected to the input of the first, that is, in a ring. Typically a pattern consisting of a single 1 bit is circulated, so the state repeats every N clock cycles if N flip-flops are used. It can be used as a cycle counter of N states. Johnson counter A Johnson counter (or switchtail ring counter, twisted-ring counter, walking-ring counter, or Moebius counter) is a modified ring counter, where the output from the last stage is inverted and fed back as input to the first stage. A pattern of bits equal in length to twice the length of the shift register thus circulates indefinitely. These counters find specialist applications, including those similar to the decade counter, digital to analog conversion, etc