Abstract: Methods of testing, diagnosing, or assessing the functionality of switches of an electric motor control system and/or a phase loss of an electric motor, and electric motor systems/motor control systems employing such methods, are disclosed herein. In one example embodiment, a method of diagnosing a fault includes detecting respective phase voltage signals communicated from the first, second, and third output nodes indicative of respective phase voltages occurring at the first, second, and third output nodes, respectively, and determining whether the respective phase voltages indicate that a first fault has occurred, either with respect to one or more transistors of pairs of switching transistors or with respect to one or more of first, second, and third phase windings. The determining is based upon whether the respective phase voltage signals indicate that respective phase voltages present respectively at the output nodes are equal or substantially equal to an intermediate output voltage.