E70 x5 4x4 dsc error. OBD2 message

OBD2 message tells Transmission control module communication failed. I have checked transmission has TCM integrated with valve body having barrel electrical connection at transmission case. Disconnected and reconnected barrel connection. I also installed fresh 100 AH battery. And cleared code using OBD2 and start engine. No more dsc 4x4 error. I had not driven this x5 for a long time knowing that battery drains quickly. TCM module requires stable voltage and current and it might have shutdown itself.