July 1: So it begins. Don't worry, this is not in the correct legal jurisdiction!
Display Signal Circuit Between Navigation ECU and Multi-display: Wiring Diagram
WARNING: This page is about a different car, the 2007 Lexus RX 350. However, it is still accessible from the selected car via links, so may be relevant.
Fig 1: Identifying Display Signal Circuit Between Navigation ECU & Multi-Display Wiring Diagram