Lexus 2003 LS Owner's Manual page 275

In the following cases, the warning messages appear and
the preset speed automatically cancels out. When
dynamic laser cruise control is restored, the warning
messages turn off and dynamic 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 wipers are operated at high or low speeds (including
high and low speed operations with the wiper lever in the
"AUTO" position.)
c. The driving pattern selector switch is set to "SNOW" mode.
d. The anti–lock brake system is activated by automatic
braking. (The warning tone sounds.)
e. The sensor does not operate properly because a foreign
matter sticks to the sensor.
NOTICE
If the preset speed automatically cancels out for other
than the above reasons, do not operate the dynamic
laser cruise control and have your vehicle checked by
your Lexus dealer at the earliest opportunity.
STARTING AND DRIVING
3 Resetting to a faster speed
Press the control lever upward in the "RES/ACC" direction and
hold it. Release the lever when the desired speed is attained.
While the lever is held upward, the vehicle will gradually gain
speed.
A quicker way to reset the speed is to accelerate and then
press the control lever downward in the "SET/COAST"
direction.
4 Resetting to a slower speed
Press the control lever downward in the "SET/COAST"
direction and hold it. The vehicle starts to decelerate from the
speed at which the lever is operated. Release the lever when
the desired speed is attained. While the lever is held
downward, the vehicle speed will gradually decrease.
A quicker way to reset the preset speed is to depress the brake
pedal and then press the control lever downward in the
"SET/COAST" direction.
If the control lever is released when the vehicle speed exceeds
the upper limit of the preset speed traveling downhill while you
are pressing the control lever downward, the system will
memorize the upper limit of the preset speed as a preset
speed.
Shifting the transmission from "D" to "4" will not slow your
vehicle as it does when the dynamic laser cruise control is not
engaged. To slow down, reset the cruise control to a slower
speed with the cruise control lever or depress the brake pedal.
If you use the brake pedal, cruise control is cancelled.
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