Battery ECU reporting erratic module voltages

Hey folks,

Our Prius recently threw four hybrid battery fault codes (P3000, P3030, P3012 and P3013)

Initially suspected modules 2 & 3 were failing based on P3012 & P3013. Then realized the ECU was reporting wildly erratic and physically impossible voltages for those modules. See attached chart showing modules 1 and 4 holding steady, while module 2 swings 10V to -15V, and module 3 swings +10V to 25V.

Curious if anyone's seen this kind of fault before? My guess is the harness is corroded at the connector or module and/or the battery ECU is failing. Planning to open it up tomorrow to inspect.

Thanks,

Niall