2003 GMC Sierra 1500 Pickup Owner's Manual - Page 95

Door9 m d Locks m . i There are several ways to lock and unlock your vehicle. You can use the keyless entry system (if equipped). You can also use your key. To lock the door from the inside, slide the lever rearward. To unlock the door, slide the lever forward. Unlocked doors can be dangerous. Passengers - especially children - can easily open the doors and fall out of a moving vehicle. When a door is locked, the handle won't open it. You increase the chance of being thrown out of the vehicle in a crash if the doors aren't locked. So, wear safety belts properly and lock the doors whenever you drive. a Young children who get into unlocked vehicles may be unable to get out. A child can be overcome by extreme heat and can suffer permanent injuries or even death from heat stroke. Always lock your vehicle whenever you leave it. a Outsiders can easily enter through an unlocked door when you slow down or stop your vehicle. Locking your doors can help prevent this from happening. 2-8