TC reported brake fault indication illuminated at front DT car. Fault self-cleared. Train undershootby 0.3 meters in AM mode at MRB1. ATPM to headwall - ok. ~~~~~ TC reported brake fault indication illum     #3659 Check and found ACU solenoid port heavy leaking when at coast & off 750v.Replaced ACU and function check ok and brake cycle test ok. ACU-Old s/n: 1528-059  New s/n: 1535-070 Not:2155160 raise to RSW. Done by Kumar/Jun  28/04/20