Lexus GS430 User Manual page 446

STARTING AND DRIVING
In the following cases, the preset speed automatically
cancels out:
a. The vehicle speed falls below about 40km/h (25 mph).
b. If the vehicle speed drops 16 km/h (10 mph) below the
preset speed, the preset speed will also automatically be
cancelled.
c. The control lever is pressed downward in the "– SET"
direction and held at less than about 45 km/h (28 mph). (45
km/h (28 mph) is designated as a lower preset speed limit .)
If the vehicle speed falls below about 40 km/h (25 mph), the
preset speed data is cleared and you must set the speed from
the beginning.
If cancelled by the above cases, the multi−information display
shows nothing and the conventional cruise control enters the
ready mode.
If the preset speed automatically cancels out for other than the
above reasons, do not operate the cruise control. Although it
is no problem to continue driving, have your vehicle checked
by your Lexus dealer at the earliest opportunity.
422
3 Resetting to a faster speed
Press the control lever upward in the "+ RES" 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.
When the difference between the actual vehicle speed and the
set speed is less than 5 km/h (3 mph), the set speed can be
increased 1.6 km/h (1 mph) each time by pressing the control
lever upward in the "+ RES" direction quickly within 0.6
seconds.
A quicker way to reset the speed is to accelerate and then
press the control lever downward in the "– SET" direction.