Abstract: A diagnostic method and apparatus for a cable television interdiction system is provided. One or more diagnostic modes each corresponding to a particular problem or state associated with the interdiction unit may be entered into by the interdiction unit. If a diagnostic mode is detected, the television signal provided to a television signal receiving apparatus, e.g., a television set, is disabled for a specified length of time. Thereafter, depending upon the diagnostic mode detected, either the television signal provided to the receiving apparatus and/or a light-emitting device, e.g., a light-emitting diode (LED), is pulsed a specified number of times corresponding to the detected diagnostic mode. The cycle of disabling the television signal provided to the receiving apparatus and pulsing either or both the television signal provided to the receiving apparatus and/or the LED is repeated until a transaction is received from the headend cancelling the diagnostic mode.