GMC Sierra 2010 Owner's Manual page 113

If your child restraint has the LATCH system, see Lower
Anchors and Tethers for Children (LATCH) on
page 2 50 for how and where to install your child
restraint using LATCH. If you secure a child restraint
using a safety belt and it uses a top tether, see Lower
Anchors and Tethers for Children (LATCH) on
page 2 50 for top tether anchor locations.
Do not secure a child seat in a position without a top
tether anchor if a national or local law requires that the
top tether be anchored, or if the instructions that come
with the child restraint say that the top strap must be
anchored.
In Canada, the law requires that forward-facing child
restraints have a top tether, and that the tether be
attached.
You will be using the lap-shoulder belt to secure the
child restraint in this position. Follow the instructions
that came with the child restraint.
1. Move the seat as far back as it will go before
securing the forward-facing child restraint.
2. Put the child restraint on the seat.
3. Pick up the latch plate, and run the lap and
shoulder portions of the vehicle's safety belt
through or around the restraint. The child restraint
instructions will show you how.
4. Push the latch plate into the buckle until it clicks.
Make sure the release button is positioned so you
would be able to unbuckle the safety belt quickly if
necessary.
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