Steering Lock Motor Drive Power Circuit: Description
WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.
The steering lock ECU is connected to the power source control ECU and ID CODE BOX The steering lock ECU cannot activate the motor unless it receives permission signals from both ECUs (The power source control ECU permits the steering lock ECU to supply power to activate the motor.)