Circuit Description
WARNING: This page is about a different car, the 2002 Lexus LX 470. However, it is still accessible from the selected car via links, so may be relevant.
The door courtesy switch comes ON when the door is opened and goes OFF when the door is closed. Furthermore the door courtesy switch circuit has terminal +B connected inside the theft deterrent ECU. Battery positive voltage is applied to connector T6 terminal No. 4 (DSWD) of the theft deterrent ECU when all doors are closed (i.e. when the door courtesy switches of all doors are OFF). See Fig 1.