GMC 2006 Envoy Owner's Manual page 56

2. If the child restraint manufacturer recommends that
the top tether be attached, attach and tighten the
top tether to the top tether anchor, if equipped.
Refer to the child restraint instructions and
the following steps:
2.1. Find the top tether anchor.
2.2. Route and tighten the top tether according to
your child restraint instructions and the
following instructions. For five-passenger
vehicles, if your vehicle is equipped with a
cargo shade, route the top tether between
the seatback and the cargo shade.
1-50
If the position you are
using does not have a
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
head restraint and you
are using a dual tether,
route the tether over
the seatback.
See Rear Seat Operation on page 1-9.
For seven-passenger vehicles that have
adjustable head restraints, raise the
head restraint and route the single tether
under the head restraint and in between the
head restraint posts.
3. Push and pull the child restraint in different
directions to be sure it is secure.
For five-passenger
vehicles that have a head
restraint, fold down the
head restraint and
route the single tether
under the head restraint
and in between the
head restraint posts.
If the position you are
using has a head restraint
and you are using a
dual tether, route the tether
around the head restraint.