Circuit Check for Monitoring Isolation Resistance

A method of circuit check for isolation monitoring is provided. The method includes providing an isolation monitoring circuit to measure isolation resistance between high voltage domain and vehicle chassis and providing a test switch being part of the isolation monitoring circuit. The method also includes providing a sub-switch-circuit having a chassis switch, a constant current source, a resistor positioned between the chassis switch, and a chassis ground. The test switch is movable between a first test switch position and a second test switch position. The method also includes instructing the test switch to move to a first position. In addition, the method includes determining a current source voltage, and determining a position of the test switch based on the current source voltage.