Master fault and BCU fault at car frontM1 and rear M1 at bogey 1 and 2. Fault cleared arriving YIS SB. Master fault intermittently illuminated. ~~~~~ 1563 & 1564 Master and BCU fault at bogie 1 and 2. Fault cleared arriving YISSB. Master fault intermittently illuminated.  1563 & #1564 found FC 308/330/331. Replaced ACU & function test - OK. Brake pressure checked - OK. No air leak found. Limited movement/depot shunting - OK. No residual pressure at COAST. ACU S/N :   1563                1564 OLD  :     1302/131            1302/130 NEW  :     1012/015            1244/102  Sarma/Lee PT 44274