2003 GMC Yukon Owner's Manual - Page 113

Ignition Positions With the key in the ignition switch, you can turn the key to four different positions. Notice: If your key seems stuck in LOCK and you can't turn it, be sure you are using the correct key; if so, is it all the way in? Turn the key only with your hand. Using a tool to force it could break the key or the ignition switch. If none of these works, then your vehicle needs service. C (RUN): This is the position for driving. D (START): This position starts your engine. Retained Accessory Power (RAP) Your vehicle may be equipped with a Retained Accessory Power (RAP) feature which will allow certain features on your vehicle to continue to work up to 10 minutes after the ignition key is turned to OFF. Your radio, power windows, sunroof (if equipped), and OnStar® System (if equipped) will work when the ignition key is in RUN or ACCESSORY. Once the key is turned from RUN to LOCK, these features will continue to work for up to 10 minutes or until a door is opened. A (LOCK): This position locks your ignition and transmission. It's a theft-deterrent feature. You will only be able to remove your key when the ignition is turned to LOCK. B (ACCESSORY): This position lets you use things like the radio, power windows and the windshield wipers when the engine is off. 2-19