A diagnostic system for a DC-DC voltage converter having a high voltage switch, a low voltage switch, and a DC-DC voltage converter control circuit is provided. The system includes first and second tri-state buffer ICs and a microcontroller. The first tri-state buffer IC receives a first shutdown indicator voltage from the DC-DC voltage converter control circuit indicating that a first plurality of FET switches in a high side FET IC and a second plurality of FET switches in a low side FET IC have been transitioned to an open operational state. The first tri-state buffer IC outputs a second shutdown indicator voltage to the microcontroller that indicates that the first and second plurality of FET switches have been transitioned to the open operational state.