Train undershoot platform by 2.97 metresin Auto mode. Proceeded in ATPM mode to the headwall. Train undershoot platform by 2.97 metres in Auto mode. Proceeded in ATPM mode to the headwall. ~~~~~ Train undershoot platform by 2.97 metres     #3559 Check no fault code.Conducted brake cyclic tes ok.No sign of slow brake release.BCP within criteria,Check ER show #1559 BCP was 1.45bar and the rest of M car was at 0.21~0.24bar,To follow up check on brake at #1559. 0020 raise to follow up. Checked by Zulq  03/08/22 To follow up check on 1559 ACU for any abnormalities Check and found ACU was swap by others.ACU was indicate from #2560.Conduct brake cyclic ACU no abnormalities.For preventive measure replace ACU.Function test ok and BCP within criteria. ACU:- Old: 1024-030 New: 1310-136 Not: 2404954 raise. Done by Saini/Zulq  03/08/22