TIMS showed BCU fault at car 1646. Trainunable to proceed in AM & ATPM mode. TC operated STBS to pr oceed to TIB2 to disembark pax. ~~~~~ 1646 TIMS showed BCU fault. Train  unable to proceed in AM & ATPM mode. TC operated STBS to proceed to TIB2 to disembark pax. (L3) L3 1646 ER D/L & found FC 301/307/308/314/330/331. #1646 stuck brake, STBS activated & BIC isolated. Replaced BCU & brake cyclic test - OK. Wiring terminals at ACU/BCU checked - OK. No air leak from ACU. Brake shoes checked - OK.  Au TK/Chan SW 44795 #1646 BCU S/N : OLD : 1509163 NEW : 1517187