How To Proceed With Troubleshooting
WARNING: This page is about a different car, the 2005 Lexus GS 430 and 2005 Lexus GS 300. However, it is still accessible from the selected car via links, so may be relevant.
HINT:
The ECU of this system is connected to the multiplex communication system. Therefore, before starting troubleshooting, make sure to check that there is no trouble in the multiplex communication system, refer to MULTIPLEX COMMUNICATION SYSTEM - DIAGNOSTICS .