2010 GMC Acadia Owner's Manual - Page 274

9-18 Driving and Operating Notice: Using a tool to force the key to turn in the ignition could cause damage to the switch or break the key. Use the correct key, make sure it is all the way in, and turn it only with your hand. If the key cannot be turned by hand, see your dealer/retailer. items plugged into the accessory power outlets. This position unlocks the ignition and steering wheel. Use this position if the vehicle must be pushed or towed. Ignition Positions ( (LOCK/OFF): This position locks the ignition and transmission. The key can be removed in LOCK/OFF. The shift lever must be in P (Park) to turn the ignition switch to LOCK/OFF. The steering can bind with the wheels turned off center. If this happens, move the steering wheel from right to left while turning the key to ACC/ACCESSORY. If this doesn't work, then the vehicle needs service. ACC (ACC/ACCESSORY): This is the position in which you can operate the electrical accessories or The ignition switch has four different positions. In order to shift out of P (Park), the ignition must be in ON/RUN or ACC/ ACCESSORY and the brake pedal must be applied. R (ON/RUN): This position can be used to operate the electrical accessories and to display some instrument panel warning and indicator lights. The switch stays in this position when the engine is running. The transmission is also unlocked in this position. If you leave the key in the ACC/ ACCESSORY or ON/RUN position with the engine off, the battery could be drained. You may not be able to start the vehicle if the battery is allowed to drain for an extended period of time. / (START): This is the position that starts the engine. When the engine starts, release the key. The ignition switch will return to ON/RUN for driving.