TC reported brake fault at rear M1 car.Fault self cleared after train came to a stop. Train was abl e to depart in AM to next station. ERS-12 ~~~~~ TC reported brake fault at rear M1 car.     Replaced ACU due to EM to Coast air leak at solenoid v/v exhaust port.Brake cyclic test ok.All brake BCP within criteria. Old s/n: 1538165 New s/n: 1549213 Not: 2296182 raise. Done by Koh/Din.   15/7/21