Train undershoot platform in Auto mode.Proceeded in ATPM mode to the headwall. TC also reported bef ore train undershoot, TIMS showed BCU unhealthy at Front M2 car. Fault self cleared when train was alligned with the CSP ~~~~~ 3568 Train undershoot platform in Auto mode. Proceeded in ATPM mode to the headwall. TC also reported before train undershoot, TIMS showed BCU    unhealthy at Front M2 car (2568). Fault self cleared when train was aligned with the CSP.  2568 ER & FC D/L - Done. FC 308/312/314/330/331. Replaced ACU - Done. Brake pressure & ststus check - OK. 2568 ACU S/N : OLD : 1042/069 NEW : 1042/072  Chan GF/Alan/Alcus 43960