Four-Wheel Drive - 4x4 LOW
WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
4x4 LOW allows for maximum pulling capacity. Shifting into 4x4 LOW causes the range sleeve to move rearward and engage the planetary gear to achieve gear reduction. The result is that the output shaft now turns more slowly than the input shaft. This action increases the pulling capacity available to the wheels.