DC link undervoltage detectedy by software
Check the vehicle HV DC-bus voltage for voltages below operating limits. If no voltage at the inverter terminals, check for blown aux inverter fuse in the Junction box. If fuse in fine, check for BMU faults for not closing the Battery contactor.
What you'll see
No driver-visible symptom recorded.
System reaction
System will enter error mode and switches OFF. KL15 needs to be reset, to operate the device again under normal voltage conditions.
Diagnostic depth
Input voltage voltage sensor measures a lowvoltage below 350V
Voltage in the Vehicle HV DC bus is below the operating limits of the device. This could be because of a blown HV fuse in the Junction box. Also, when HV battery contactors are not closed while trying to run the compressor. The battery contactors might not have closed due to other faults in the VCB system.