The present invention discloses an apparatus and method for diagnosing hardware in an insulation resistance monitoring system for a vehicle. In at least one embodiment, an apparatus for diagnosing electronics in the insulation resistance monitoring system is provided. The apparatus includes a controller for being electrically coupled to a plurality of electronics including a plurality of switches that are electrically coupled to a positive branch and to a negative branch in a high voltage network and a low voltage network. The plurality of electronics is configured to perform insulation resistance monitoring in the vehicle. The controller is further configured to at least one of activate and deactivate any number of the plurality of switches to determine an overall voltage of the positive branch and the negative branch. The controller is further configured to detect a fault in at least one of the positive branch and the negative branch that corresponds to a failure of any one of the plurality of electronics based on the overall voltage.