WARNING: This page is about a different car, the 2003 Lexus LS 430. However, it is still accessible from the selected car via links, so may be relevant.
TILT AND TELESCOPIC STEERING SYSTEM - TROUBLESHOOTING
Control ECU
Master control system
Sub control system
Tilt and telescopic steering ECU
Tilt and telescopic steering system
Seat position memory system
Fig 1: Identifying Light Control Back Up Bus Circuit Diagram