In at least one embodiment, an apparatus for monitoring isolation resistance in a vehicle is provided. The apparatus includes at least one controller that is configured to at least one of activate and deactivate any number of the plurality of switches and to perform a plurality of measurements on a high voltage system. The at least one controller is further configured to determine an isolation resistance between the high voltage system and the low voltage system based on the plurality of measurements and to determine a first resistance between the positive branch and a ground of the low voltage system based at least on the isolation resistance. The at least one controller is further configured to determine whether the isolation resistance of the high voltage system is exhibiting a symmetric failure, or an asymmetric failure based at least on the first resistance.