auto-mode-always-4wd-t548182.html
This was a good discussion on the AUTO mode. AUTO shifts power from the rear wheels to the front as needed. It functions as an automatic all-wheel drive. It engages when necessary, shifting up to 50% of the torque forward. It does not shift left-to-right, only front to rear. The differential is unlocked and the power is variable, anywhere from 100% rear to 50% front/50% rear
In that post, there were some people incorrectly stating that all AUTO does is engage 4HI when there's slippage. That's not the case. In 4HI, the system locks at 50/50 front rear and has no variation...it's an off-road mode. AUTO is infinitely variable, safe to use all the time, dry or wet. To save a little fuel economy or to take a smog test, you can put it in 2WD. I personally use AUTO all the time.