Train prep 1621 BCU fault. ~~~~~ Train prep 1621 BCU fault.    RSD: Checked found 1621 stuck brake unable to release. TIMS shows BCU release fault. To rectify.  As above mention 1621 fc308,314,330,331. check and found 1621 brake fault. Swap ACU from 1621 to 2621, Tested and Found fault transfer and ACU leak and hunting at AC solenoid, Replace ACU ok. check brake apply and release ok, brake and function test status ok, BCP within criteria Done by Haslan/Asruddin 45134