Combine 1 cup crushed pretzels, 3 tablespoons sugar, and 1/4 cup melted butter. Press mixture on bottom of a 13- x 9-inch pan coated with cooking spray. (Mixture will be crumbly.)
Bake at 350° for 15 minutes; cool completely.
Beat softened cream cheese, 5 tablespoons sugar, and 1 teaspoon vanilla at low speed with an electric mixer until sugar dissolves. Fold in whipped topping; spread over pretzel layer.
Stir together gelatin and 2 cups boiling water until dissolved; add strawberries. Chill 1 hour or until partially set. Spread gelatin mixture over cream cheese layer; chill 8 hours or until set.
Stir together sour cream and remaining 1/4 cup sugar; spread over top of strawberry layer; sprinkle with pecans.
Note: Reduce sodium by substituting low-sodium pretzels for regular.