This 16-channel fault insertion switch is primarily intended for routing simulated fault conditions in automotive and aerospace applications involving the reliability testing of safety critical controllers. Designed to route different fault conditions between the test fixture and the equipment under test, including: Open-circuit Short-circuit between UUT connections Short-circuit to other signals such as power, ignition and ground via fault buses Through relays on each channel enable signals to the UUT to be held open-circuit. Fault Insertion Buses allow any channel to be shorted to any other channel and also enable any channel to be connected to an external fault condition. The module has four fault buses that allow an external signal level such as power, ignition and ground to be inserted as a fault condition. For further flexibility, each fault bus includes a changeover switch to select one of two fault conditions. The default state of the unit is with all through relays closed and all fault insertion relays open, giving an un-interrupted path between the test fixture and the equipment under test.