I removed the right side switch bank and completely disassembled it. This picture is of the circuit board for it. The two center positions are labelled "display on" & "display off". There is also another position on the board which is unused on our vehicles labelled "acc". I am assuming it is for the cruise switch on the Siennas. This may also be developed for another function for us as well.
When I reassembled the switch bank, I installed two white pieces which are used to transfer the pressure applied to the switch, to the circuit board contacts. I got these from the extra switch bank I just bought, and are needed for the switch to function. The switch does not fit 100%, but does work & I can feel the button press to detent & return. It would definitely be nice to have the intended switch installed there.
Anyway, food for thought. I thought you all might like to know...