I suspect no one here is actually reading his post? - he's asking about a 'motion sensor' not a 'timer'. I can't comment on cable boxes, but a number of TV's stupidly added motion sensors (which could ALWAYS be disabled) to turn the set off if it thought no one was in the room watching the TV.
Part of the installation including turning it OFF, along with any other stupid 'timers', and various other useless and unwanted 'features', such as auto-brightness.
All the useless features are normally turned ON by default, and result in countless service calls to new TV's (unless installed properly).