IG Power Source Circuit: Description
WARNING: This page is about a different car, the 2008 Toyota Tundra. However, it is still accessible from the selected car via links, so may be relevant.
When the ignition switch is turned ON, the IG power source circuit supplies positive (+) voltage to the multiplex tilt and telescopic ECU.
The multiplex tilt and telescopic ECU also receives ignition switch signals via this circuit.