TRAC OFF Indicator Light, TRAC OFF Switch Circuit: Description
WARNING: This page is about a different car, the 2007 Lexus RX 350. However, it is still accessible from the selected car via links, so may be relevant.
The skid control ECU is connected to the combination meter via CAN and multiplex communications. When the TRAC OFF switch (Traction OFF switch) is turned on, the TRAC OFF indicator light will come on.