PREHEAT oven to 350ºF. Drain pineapple, reserving 1 cup of the juice; set pineapple aside. Prepare cake batter as directed on package, substituting 1 cup reserved juice for 1 cup of the water. Pour batter into greased 15x10x1-inch baking pan.
BAKE 15 to 18 min. or until wooden toothpick inserted in center comes out clean. Cool completely in pan on wire rack.
ADD milk to dry pudding mix. Beat with wire whisk 2 min. or until well blended. Stir in pineapple. Spread over cake; cover with whipped topping. Sprinkle with coconut and pecans. Store in refrigerator.