3512-BCU Fault During Train Prep.To Rect ~~~~~ 3512 - BCU Fault During Train Prep.(FC 301 & 307)  3512 ER D/L found FC 301/307 (BCU Communication Error 6 & BCU Comm. Fault). Swapped #3512 BCU with #1512. Replaced #1512 with new BCU. Wheel diameter setting checked - OK. Brake pressure check - OK. Limited movement - OK. No abnormalities found.  Koon PL/Haiqal 45066 BCU S/N : (after swapped) #3512 : 1809053 #3512 : 1745020 (faulty) #1512 : 1809066 (NEW)