Interior Light Switch Signal Circuit: Description
WARNING: This page is about a different car, the 2008 Lexus IS F. However, it is still accessible from the selected car via links, so may be relevant.
The main body ECU RH receives information on the front interior light switch (marked ON/OFF).
The main body ECU LH receives information on the front interior light switch (marked DOOR).
According to the position of each switch, the main body ECU RH controls the interior lights, and the main body ECU LH controls the illuminated entry system.