Chevrolet 2002 Tahoe Owner's Manual page 96

Lockout Prevention
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.
Child Security Locks (If Equipped)
With this feature, you can lock the rear side doors so
they cannot be opened from the inside by passengers.
2-10
Your vehicle may have one of the two child security
lock labels shown.
This feature is located on the inside edge of the
rear doors.
Move the lever forward to engage the security feature.
Move the lever rearward to return the door locks to
normal operation.