Patent ID: 8497687

Claim:
Method for monitoring operation of a vehicle including a high voltage electrical system comprising an electrical energy storage device electrically connected to a plurality of switching circuits of an inverter device via a high voltage bus, the inverter device configured to transfer electric power to an electric machine via activation of a plurality of switch devices, the method comprising: during ongoing vehicle operation: monitoring electrical ground isolation of the high voltage electrical system; and detecting an electrical ground isolation fault in the high voltage electrical system; during a vehicle key-off event subsequent to detecting the electrical ground isolation fault during ongoing vehicle operation: simultaneously commanding all switch devices to open states; monitoring electrical ground isolation of the high voltage electrical system; and when the electrical ground isolation fault is not detected during said simultaneous commanding of all switch devices to open states: iteratively commanding only one of the switch devices to a short state while simultaneously commanding every other one of the remaining switch devices to open states, wherein each iteration corresponds to a different one of the switch devices being commanded to the short state; monitoring electrical ground isolation of the high voltage electrical system; when the electrical ground isolation fault is detected during one of said iterations, associating the electrical ground isolation fault with the one of the switch devices commanded to the short state during said one of said iterations.