Toyota Sienna 2010 Owner's Manual page 151

1-7. Safety information
Child restraint systems with a top tether strap (second seat)
STEP 1
STEP 2
STEP 3
152
Secure the child restraint using
the seat belt or LATCH anchors.
Remove the head restraint.
Latch the hook onto the anchor
bracket and tighten the top tether
strap.
Make sure the top tether strap is
securely latched.
Hook
Top tether strap
Anchor bracket
Replace the head restraint.