Lexus 2003 LS Owner's Manual page 143

A Replace the belt assembly (including bolts) if it has
been used in a severe impact. The entire assembly
should be replaced even if damage is not obvious.
Front seat belt buckle illumination
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Opening the driver's door lights up the driver's seat belt
buckle for easy use. The same applies for the front
passenger's door and seat belt buckle.
The light remains on for 15 seconds after the door is closed,
but goes off immediately when all doors are locked.
COMFORT ADJUSTMENT
Fastening front and rear seat belts
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Adjust the seat as needed and sit up straight and well back
in the seat. To fasten your belt, pull it out of the retractor
and insert the tab into the buckle.
You will hear a click when the tab locks into the buckle.
The seat belt length automatically adjusts to your size and the
seat position.
The retractor will lock the belt during a sudden stop or on
impact. It also may lock if you lean forward too quickly. A slow,
easy motion will allow the belt to extend, and you can move
around freely.
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