The present disclosure relates to security mechanisms for electric motors and associated systems. For example, the present technology includes a powertrain assembly having (1) a motor having multiple sets of coils; (2) a drive circuitry electrically coupled to the multiple sets of coils; and (3) a security unit electrically coupled to the drive circuitry and the multiple sets of coils. The security unit is configured to short-circuit at least one set of the multiple sets of coils responsive to a signal from a controller. The signal indicates that the motor is, or has been, turned off.