2004 GMC Yukon Owner's Manual - Page 107

To use one of the locks do the following: 1. Open one of the rear doors. 2. To engage the rear door security locks, move the lever forward. 3. To disengage the lock, move the lever rearward. 4. Close the door. 5. Do the same thing to the other rear door. The rear doors of your vehicle cannot be opened from the inside when this feature is in use. If you want to open the rear door while the security lock is engaged, unlock the door and open the door from the outside. Liftgate {CAUTION: It Can be dangerous to drive with the liftgate glass, liftgate or rear doors open because carbon monoxide (CO) gas can come into your vehicle. You can not see or smell CO. It can cause unconsciousness and even death. If you must drive with the liftgate glass, liftgate or rear doors open or if electrical wiring or other cable connections must pass through the seal between the body and the liftgate glass, liftgate or rear doors: • Make sure all other windows are shut. • Turn the fan on your heating or cooling system to its highest speed with the setting on VENT or OUTSIDE AIR. That will force outside air into your vehicle. See Climate Control System on page 3-22. • If you have air outlets on or under the instrument panel, open them all the way. See Engine Exhaust on page 2-41. Lockout Protection This feature protects you from locking your key in the vehicle when the key is in the ignition and a door is open. If the power lock switch is pressed when a door is open and the key is in the ignition, all of the doors will lock and then the driver's door will unlock. 2-13