Lexus 2003 LS Owner's Manual page 148

COMFORT ADJUSTMENT
CAUTION
A After inserting the tab, make sure the tab and buckle
are locked and that the belt is not twisted.
A Do not insert coins, clips, etc. in the buckle as this
may prevent you from properly latching the tab and
buckle.
A If the seat belt does not function normally,
immediately contact your Lexus dealer. Do not use
the seat until the seat belt is fixed. It cannot protect
an adult occupant or your child from injury.
134
Seat belt pretensioners
16L329b
The seat belt pretensioners other than that for the rear
center belt are designed to be activated in response to a
severe frontal impact.
When the airbag sensor detects the shock of a severe frontal
impact, the seat belts are quickly drawn back in by the retractor
so that the belts snugly restrain the seat occupants.
The front passenger seat belt pretensioner will not activate if
there is no passenger sitting in the front passenger seat.
However, the front passenger seat belt pretensioner may
activate if luggage is put in the seat, or the seat belt is buckled
up regardless of the presence of the occupant in the seat.
The outside rear seat belt pretensioners are activated even
with no passengers in the outside rear seat.
Collisions occurring at certain speeds and angles may cause
the seat belt pretensioners and SRS airbags not to operate all
together.