I bought that tester from the dealer toolbox and never use it. If im getting power to the motor and its not spinning thats all i need to know so i just replace the motor, no need to spend time on further diagnosis.
To clarify for others who will be testing. These motors are supplied with line voltage power all the time. They only energies to the selected "speed" when the correct low voltage tap is energized. Condemning an ECM motor only because it is getting 120V and not spinning could lead to a mis-diagnosis.