A method for characterizing a stick-slip or stiction condition in an electrically-assisted steering system includes transmitting a first steering control signal from a controller to a rotary actuator as a periodic steering conditioning signal, receiving a second steering control signal via a steering assist motor throughout the test to electrically assist steering, transmitting a third steering control signal to the rotary actuator to cause alternate rotation of the steering shaft to a target angle rate at constant acceleration/deceleration, and measuring a steering torque output from the rotary actuator. A control action is executed when a difference in local maximum and minimum peak amplitudes of the steering torque output exceeds a calibrated threshold difference indicative of stiction. A system includes a rotary actuator, the steering system, a torque transducer operable for measuring a steering torque imparted to the steering shaft by the rotary actuator, and the controller noted above.