My dads 06 Explorer wont come out of 4x4 hi if it turns on automatically. He has to put it in 4x4 hi, then press 4x4 auto to get back to 2wd.
Its a southern truck, zero rust, 70k miles, very well taken care of.
For example
If the road is wet, or any wheel slip detected, 4x4 auto kicks in...