Pattern Select Switch Snow Mode Circuit: Description
WARNING: This page is about a different car, the 2006 Lexus GS 430. However, it is still accessible from the selected car via links, so may be relevant.
Cowl side J/B ECU receives pattern select switch information, and sends it through the multiplex communication system and CAN system to the ECM.
ECT SNOW is the system that operates the throttle motor to control engine output to reduce skidding of the driving wheels, guarantee takeoff acceleration, driving straightness and turning stability.