Fuses are in the two fuse boxes, one inside and one under the hood. If we could tell what's wrong without doing any diagnosis, there would be no need for mechanics. Brake light switches are common, as are clock springs under the steering wheel. The place to start is by stating the problem. Does it not work at all? Does the light on the dash turn on? Does it do a poor job of holding the speed? Does it fail to cancel or resume? Does it cut out when you driver over bumpy roads?