2003 Hummer H2 Owner's Manual - Page 116

D While still pressing the button, move the lever forward as far as it will go. Let go of the button and the lever. Leaving Your Vehicle With the Engine Running CAUTION: It can be dangerous to leave your vehicle with the engine running. Your vehicle could move suddenly if the shift lever is not fully in PARK (P) with the parking brake firmly set. With your transfer case in NEUTRAL, your vehicle will be free to roll, even if your shift lever is in PARK (P). So be sure the transfer case is in a drive gear -- not in NEUTRAL. And, if you leave the vehicle with the engine running, it could overheat and even catch fire. You or others could be injured. Don't leave your vehicle with the engine running unless you have to. 3. Turn the ignition key to LOCK. 4. Remove the key and take it with you. If you can leave your vehicle with the ignition key in your hand, your vehicle is in PARK (P). 2-34