Prepare and bake the cake according to package directions, using a greased 13x9x2 inch baking pan. Cool on a wire rack.
Meanwhile, prepare pudding according to package directions; pour into a 13x9x2in. dish.
Tear cake into small pieces and gently push down into the pudding. Drizzle with 3/4 cup of chocolate syrup. Spread with whipped topping. Drizzle with remaining chocolate syrup. Sprinkle with pecans. Refrigerate until serving.