Lexus 2004 LS430 Owner's Manual page 360

STARTING AND DRIVING
In the following cases, the warning messages appear and
the preset speed automatically cancels out. When
dynamic radar/laser cruise control is restored, the
warning messages turn off and dynamic radar/laser
cruise control enters "RADAR READY" mode.
a. The slip indicator light blinks and a warning tone sounds.
(This occurs when the vehicle is about to skid.)
b. The driving pattern selector switch is set to "SNOW" mode.
c. The anti- lock brake system is activated by automatic
braking. (The warning tone sounds.)
d. The sensor does not operate properly because a foreign
matter sticks to the sensor.
Dynamic radar cruise control—
e. The wipers are operated at high speed (including high
speed operation with the wiper lever in the "AUTO" position.)
Dynamic laser cruise control—
f. The wipers are operated at high or low speeds (including
high and low speed operations with the wiper lever in the
"AUTO" position.)
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NOTICE
If the preset speed automatically cancels out for other
than the above reasons, do not operate the dynamic
radar/laser cruise control. Although it is no problem to
continue driving, have your vehicle checked by your
Lexus dealer at the earliest opportunity.