Intermittent BCU fault at rear M1 car. ~~~~~ 1542 ACU replaced - Done. Security check & air leak check - OK. Function check - OK. Brake cyclic test - Done. Brake cylinder pressure check - OK. 1542 ACU S/N : OLD : 1042/076. NEW : 1310/142.  Boopathy/Nelson. 15/03/2020.