2007 GMC Sierra 1500 Pickup Owner's Manual - Page 136

C (RUN): This is the position for driving. The battery could be drained if you leave the key in the ACCESSORY or RUN position with the engine off. You may not be able to start your vehicle if the battery is allowed to drain for an extended period of time. D (START): This position starts your engine. Key Release Button (Manual Transmission) The ignition key cannot be removed from the ignition of manual transmission vehicles unless the key release button is used. Key In the Ignition Never leave your vehicle with the keys inside, as it is an easy target for joy riders or thieves. If you leave the key in the ignition and park your vehicle, a chime will sound, when you open the driver's door. Always remember to remove your key from the ignition and take it with you. This will lock your ignition and transaxle. Also, always remember to lock the doors. The battery could be drained if you leave the key in the ignition while your vehicle is parked. You may not be able to start your vehicle after it has been parked for an extended period of time. To remove the key on manual transmission vehicles, turn the key to ACCESSORY, then press the button and turn the key to LOCK. Do not hold the button in while turning the key to ACCESSORY. Pull the key straight out. 136