Steering Lock Motor Drive Power Circuit: Description
WARNING: This page is about a different car, the 2011 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.
The steering lock ECU is connected to the main body ECU and certification ECU. The steering lock ECU cannot activate the motor unless it receives permission signals from both ECUs. (The main body ECU permits the steering lock ECU to supply power to activate the motor.)