TC reported bcu emergency fault at FM1 car. Train performance ok. ERS-15 ~~~~~ 1676 TC reported bcu emergency fault. Train performance ok.  1676 FC BCU emergency bog 1 & 2 BCP fault. ER shows BCP slightly high & slow to release. Measure EMV - OK. Swapped 1676 ACU with 2676. Installed new ACU at 2676. 1676 ACU: Old: 1447/051 New: 1434/021(swapped from 2676) 2676 ACU: New: 1434/019 Lee JC 44971