1998 GMC Envoy Owner's Manual - Page 66

Power Door Locks Rear Door Security Lock With this feature,you can lock the rear doors so they can't be openedfrom the inside by passengers. Move the lock up to lock the doors and down to release the door locks. Lockout Prevention The power door lock switch is located the armrest. on Remove the ignition key and press LOCK to lock all the doors at once. To protect you from locking your key in the vehicle, this feature stopsthe power door locks from locking when the key is in the ignition and a door is open. If the power lock switch is pressed when a dooris open and the key is in the ignition, all the doors will lock and then the driver's door will unlock. To unlock the doors, press theraised area next to the key symbol. The lever on eachrear door works only that door's lock. 2-5