Combine the pecans, brown sugar and butter in a small saucepan over medium-high heat; bring to a boil, stirring constantly.
Boil gently for exactly 30 seconds.
Spread the hot pecan mixture in the bottom of the cooled pie shell; let stand until cool.
Combine the whipped topping mix, 1 cup of the milk, vanilla and dry pudding mix in a large mixing bowl; beat at high speed for about 6 minutes or until thickened and firm.
Add the remaining 13/4 cups milk and blend at low speed.
Beat at high speed for 2 minutes.
Stir in 1 cup of the coconut and spoon into the prepared pie shell.
Chill, covered, for at least 4 hours or until firm.
Sprinkle with the remaining 1/2 cup coconut.