2506 : BCU Fault. To check & rectify. (D ~~~~~ 2506 : BCU Fault(DT check).  2506 ER D/L - Done. Replaced ACU & function check - OK. Brake cyclic test - OK. No air leak found on ACU - OK. 2506 ACU S/N :          OLD              NEW                      1240/099         1038/062 RF :                 1902/683         1722/905 (MOD 3) RC :                 1920/088         1722/943 (MOD 3) EM :                 1850/635         1722/856 (MOD 3) AF :                 2011/832         2018/537 (MOD 4) AC :                 2011/827         2018/597 (MOD 4)                   (All SV MOD 4)  Sarma/Nelson 44044