System Description
WARNING: This page is about a different car, the 2012 Lexus LS 460. However, it is still accessible from the selected car via links, so may be relevant.
When the reverse signal is sent from the TCM through the CAN (can communication) line to the front door ECU LH and RH, the front door ECU LH and RH activate the outer rear view mirror LH and RH reverse shift-linked function.
HINT:
The reverse shift-linked function will not occur when the mirror master switch is in the neutral position (OFF).