Lexus 2004 LS430 Owner's Manual page 353

D The millimeter wave radar sensor automatically
detects dirt if it is sticking to the front of the sensor
or grille cover of your vehicle, and if detected, a
message is shown on the multi-information display.
However, if the sensor or grille cover is covered with
a metallic vinyl bag, icicle, snowflakes, etc., dirt may
not be detected, resulting
vehicle-to-vehicle distance. Continue driving with
due care to the vehicle ahead. If dirt is detected, the
dynamic radar cruise control
automatically cancelled. Always keep the sensor and
grille cover clean.
Dynamic radar cruise control should not be used in the
following conditions, to avoid serious injury or death.
D In bad weather (such as rain, fog, snow, sandstorms,
or when raindrops or snowflakes get in the millimeter
wave radar sensor or the grille cover), the
vehicle-to-vehicle distance will not be measured
in improper
accurately.
If the wipers are operated at high speed (including the
high speed operation with the wiper lever in the
function is
"AUTO" position), dynamic radar cruise control is
automatically cancelled. (In the case of the low speed
operation and intermittent wiper operation, it is not
cancelled.)
automatically cancelled when the measurement is
extremely unstable due to bad weather.
D On the roads in heavy traffic or at sharp bends:
As an appropriate speed cannot be maintained,
serious injury or death could result.
D On slippery road surfaces (icy or snow-covered road
surfaces):
The tires will race and you will be unable to control.
STARTING AND DRIVING
Dynamic radar cruise control is
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