GMC Cadillac XT4 2019 Owner's Manual page 102

If the position you are
using does not have a
headrest or head restraint
and you are using a single
tether, route the tether
over the seatback.
If the position you are
using does not have a
headrest or head restraint
and you are using a dual
tether, route the tether
over the seatback.
If the position you are
using has an adjustable
headrest or head restraint
and you are using a single
tether, raise the headrest
or head restraint and route
the tether under the
headrest or head restraint
and in between the
headrest or head restraint
posts.
SEATS AND RESTRAINTS
If the position you are
using has an adjustable
headrest or head restraint
and you are using a dual
tether, raise the headrest
or head restraint and route
the tether under the
headrest or head restraint
and around the headrest or
head restraint posts.
3. Before placing a child in the
child restraint, make sure it is
securely held in place. To check,
grasp the child restraint at the
LATCH path and attempt to
move it side to side and back
and forth. There should be no
more than 2.5 cm (1 in) of
movement for proper
installation.
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