1. A method, comprising: in a control system configured to control a torque converter comprising a pump and a turbine, during a torque converter operating condition in which torque is applied to the pump and rotational speed of the turbine is at or near zero: determining a difference between a rotational speed of the pump and the rotational speed of the turbine; and initiating control of an operating temperature of the torque converter in response to the difference between the rotational speed of the pump and the rotational speed of the turbine.