In a food processor, combine the orange, raisins and pecans. Cover and process until mixture is finely chopped; set aside.
In a large bowl, cream butter and sugar until light and fluffy. Beat in eggs and vanilla until well blended. Combine the flour, baking soda and salt; add to creamed mixture alternately with buttermilk, beating well after each addition. Stir in orange mixture.
Pour into a greased and floured 10-in. flouted tube pan. Bake at 325° for 45-55 minutes or until a toothpick inserted in the center comes out clean. Cool for 10 minutes before removing from pan to a wire rack to cool completely.
In a small bowl, combine glaze ingredients until smooth; drizzle over warm cake.