Lexus GS300 1998 Owner's Manual page 193

COMFORT ADJUSTMENT
16G054
2. To remove the child restraint system, press the
buckle–release button and allow the belt to retract.
16G060
If your child restraint system requires the use of a top
strap, latch the hook onto the anchor bracket and tighten
the top strap.
See the following instructions to install the anchor bracket.
180
Top strap anchors and locations