2004 GMC Envoy Owner's Manual - Page 101

{CAUTION: It can be dangerous to get out of your vehicle if the shift lever is not fully in PARK (P) with the parking brake firmly set. Your vehicle can roll. Do not leave your vehicle when the engine is running unless you have to. If you have left the engine running, the vehicle can move suddenly. You or others could be injured. To be sure your vehicle will not move, even when you are on fairly level ground, always set your parking brake and move the shift lever to PARK (P). {CAUTION: If you have four-wheel drive, your vehicle will be free to roll - even if your shift lever is in PARK (P) - if your transfer case is in NEUTRAL. So be sure the transfer case is in a drive gear - not in NEUTRAL. See Four-Wheel Drive on page 2-26. Follow the proper steps to be sure your vehicle will not move. See Shifting Into Park (P) on page 2-31. If you are pulling a trailer, see Towing a Trailer on page 4-55. 2-35