Normally the CCU came with the latest software loaded 151-0134-20-06. This software is upgraded when the dual power supply is done. Due to an additional power supply, they need to take one binary input from the system to monitor the power supplies and provide Alert 8000 if one of the power supply is dead. Before the dual power supply, they have fault code 0016 for DC contactor open and 0018 for AC contactor open. Since they took one binary input away and no more available, they decided to combine the 0016 and 0018 into one fault 0076.
The dual power supply included the AC aux contactor on K1. Since the unit does not have this aux contactor, the software see this and faulted on 0076. Down grade the software then this error will go away since the old software does not use the aux contactor to monitor whether the AC contactor is opened or closed.