Lexus 2004 GX470 Owner's Manual page 156

CAUTION
Do not use the third center seat belt with either buckle
release. Fastening only the shoulder belt or lap belt may
cause severe personal injury in case of sudden braking
or a collision.
OCCUPANT RESTRAINT SYSTEMS
STOWING THE THIRD CENTER SEAT BELT
Stow the seat belt tabs into the cover of the roof as shown
above.
Make sure the tabs are securely locked in the cover.
PULLING OUT THE THIRD CENTER SEAT BELT
Pull the belt out a little and pull the tabs out from the cover.
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