TC reported train came to a gradual stopand there was a brake fault at car rear M1. Fault self clea red and train proceeded as per normal. TC did a brake statuscheck and confirmed all brake released. ~~~~~ 1670 TC reported brake fault & train came to a gradual stop. Fault self cleared and train proceeded as per normal. TC did a brake status check and confirmed all brake released.  1670 ACU swapped to #2670. #2670 replaced with new ACU. Brake cyclic test & function check - OK.  Elfyan/Hadi 44634 #2670 ACU S/N : OLD : 1439/027 NEW : 1508/076