Originally Posted by Northerner 2
I have a fairly steep driveway and to-day when it was snow-covered my 2013 Sorento could not deal with it. Had to get out my trusty 2002 RX 300 which made it up no problem! Both vehicle have good snow tires.
When the Sorento lost traction I had people observe and the front left wheel was spinning as was the right rear wheel. Pushing the 4 WD drive button on the dash had no effect except for illuminating the orange indicator light on the dash.
The AWD system is working perfectly here.
1.)Your Sorento is operating as a FWD vehicle with an open front differential until one of the two front wheels slips.
2.)Once a front wheel slips (has no traction and can be seen spinning) the open differential on the front axle (i am oversimplifying here, but more or less this is what happens) sends torque to the spinning wheel, and none to the wheel not spinning (the not spinning wheel is the one with traction).
3.)The AWD system detects the slippage across the front axle, and engages a clutch pack which links the front and the rear axle, allowing torque to "flow" to the rear axle.
4.)Torque flows into the rear differential, which splits torque to each rear wheel.
5.)One of your rear wheels has no traction (just like in the front) and so your rear axle is unable to drive you forward because you only have one wheel with traction, and it cannot get any torque from the rear differential.
All AWD/4WD systems with a center locker, center differential, or center clutch pack will work this way. They can link the front axle and the rear axle, meaning they can send torque from front to back (or vice versa), if they have open front and rear differentials (most do) they absolutely have no ability to send torque from side to side. The traction/stability control system is supposed to help with sending torque side to side. When a wheel spins the traction control system should apply the ABS to to that wheel, causing friction through the drivetrain and allowing the open differential to send torque to the side with traction. Not all traction control systems are created equally though and it is possible that the KIA implementation is not great.
What is probably most likely here is that your OEM tires are crap. Hyundai/KIA really put shitty tires on their vehicles at the factory, and no drivetrain or stability control system, no matter how sophisticated, can overcome an inability to grip from lousy tires. Since you've had other vehicles get up no trouble this is the most likely culprit.
Its not perfect, but my advice would be to keep some sand or some cheap all weather floor mats (I always do this) in the back of your car. If you get into this situation wedge the mat or sprinkle some sand underneath the spinning wheels and you should get them traction and get going, hopefully your momentum and catching intermittent patches of traction will take over from there. Once you wear out your OEM tires and get decent tires on you will probably never have to bother with this again.
Tires make a much larger difference than most people realize.