Problem: The blower motor operated with ancillary power and ground provided but the blower module was not getting a signal from the HVAC module. The tech found the following communication and voltage codes in all modules: B10E8, B11C2, B210A, B210B, B210C, B210D, B210E, B2199, B21DD and U0010.
Details: The tech noticed that BCM voltage was 16v even with the engine off – charging voltage was 14.2v. The tech disconnected the BCM connector to test for power and grounds – they were okay. He re-connected BCM and the blower motor worked and codes cleared until the engine was started. The tech unplugged the alternator – blower motor worked normally with the engine running. He tested the charging system and found AC voltage at the battery.
Confirmed Repair: The tech replaced the alternator and the blower problem was resolved.