2012 GMC Sierra Owner's Manual - Page 317

Driving and Operating While driving on clean dry pavement and during tight turns, you may experience vibration in the steering system. If the vehicle has StabiliTrak®, shifting into Four-Wheel Drive Low will turn Traction Control and StabiliTrak off. See StabiliTrak® System on page 9‑55. 9-41 Manual Transfer Case Front Axle The front axle engages and disengages automatically when you shift the transfer case. Some delay for the axle to engage or disengage is normal. A Four-Wheel Drive indicator light comes on when you shift into four-wheel drive and the front axle engages. See Four-Wheel-Drive Light on page 5‑26. Some delay between shifting and when the indicator light comes on is normal. The transfer case shift lever is on the floor to the right of the driver. Use this lever to shift into and out of Four-Wheel Drive.