vdc senses rotational tire slip. so if your right rear tire is spinning on snow, the vdc applies the brake to that tire to match the rotational speed of the left rear tire and forcing the car to apply torque to the other side tire. Madas don't have posi traction (sorely needed) or lockers, so it doesn't do much. If you have a 4 whl drive mada, that doesn't mean you get 4 wheels applying thrust at once. you get one front and one rear at a time- opposite sides, but since the car flips a coin to see which tires get torque when, the best you can hope for with the transfer case lock selected is right front and left rear, cycling to left front right rear, cycling back and forth. The vdc makes the slipping tires stop spinning so the vehicle can apply torque to the opposite two tires. If you turn it off, the left right cycle is random and you may get both right tires spinning followed by both left tires spinning. If you have two wheel drive all it does is reduce the rate of torque application so it doesn't slam from right to left.