Engage 4X4 in high range, then low range, then exercise the multi-terrain knob a little and lock the rear diff and go down an icey hill with down hill assist. I'm not sure if it makes the runners day but it puts a smile on my face and reassures me those functions operate.
There's a "cheap mods" thread either here or Yotatech. Sorry I can't remember which forum.
I'm not sure which gen you have but I got rid of the TPS on my 08. Changed some interior lights to LED on the other two 4Runners. Got rid of running boards, upgraded rear view mirrors etc.