Lexus 2003 LS Owner's Manual page 280

STARTING AND DRIVING
Approach warning
31L178a
CAUTION
While you are cruising in the vehicle–to–vehicle
distance control mode, if the vehicle ahead decelerates
abruptly or if another vehicle cuts in ahead of you,
inadequate braking will make your vehicle closer to the
vehicle ahead of you and the multi–information display
flashes and beeps. The driver must depress the brake
pedal to slow down, ensuring collision avoidance or
that sufficient vehicle–to–vehicle
maintained.
A The approach warning may not turn on even if the
vehicle drives closer to the vehicle ahead in the
following conditions:
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A Your vehicle and the vehicle ahead are cruising at
almost the same speed.
A The vehicle ahead is cruising at a faster speed than
yours. (The distance between the vehicles will
become longer.)
A Pay special attention to the very slow vehicle at the
end of the line in heavy traffic or at the tollgate.
A Immediately after the speed setting
A The accelerator pedal is depressed or immediately
after the release of the accelerator pedal
distance is