Wiring Diagrams: 2003
WARNING: This page is about a different car, the 2004 Lexus LX 470, 2003 Lexus LX 470, and 2002 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.
For 2003 model, see STARTER CIRCUIT under STARTING/CHARGING in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.