Ford Grand Marquis Owner's Manual page 104

Doors
Two map pockets are provided on the panels of
the front doors.
Childproof Locks for the Rear Doors
In addition to power locks, your vehicle has
childproof locks for the rear doors. If you set
these locks, the rear doors cannot be opened
from the inside of the vehicle. The doors can still
be opened from the outside when the lock knobs
are raised.
The childproof locks for the rear doors
To set the childproof lock on each rear door,
open the rear door.
Find the lever inside the label with the word
LOCKED. Move the lever up.
To release the childproof lock, open the rear
door from the outside and move the lever down.
Move the lever down.
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