Lexus 2004 LS430 Owner's Manual page 329

Vehicles with the cruise control —
When the cruise control is being used, even if you downshift
from "D" or "6" (sixth range) to "5" (fifth range), engine
braking will not be enabled because the cruise control is not
cancelled. For vehicle speed reduction, see page 326.
Vehicles with the dynamic radar/laser cruise control —
When the cruise control is being used in the conventional
(fixed speed) cruise control
vehicle-to-vehicle distance control mode, even if you
downshift from "D" or "6" (sixth range) to "5" (fifth range),
engine braking will not be enabled because the cruise
control is not cancelled. For vehicle speed reduction, see
pages 356 and 341.
D Shift into the "4" (fourth range) position. The transmission
will downshift to fourth gear when the vehicle speed is or
becomes lower than 200 km/h (124 mph) and more
powerful engine braking will be enabled.
If you drive in the "D" position: Shift the selector lever to
the "S" position and shift the lever down to the "–" position
once to select "4" (fourth range). However, when you move
the lever to the "S" position while the AI shifting control is
operating, the first shift range will be "5" (fifth range), "4"
(fourth range) or "3" (third range) because the suitable shift
range is selected depending on the driving condition.
If you drive in the "S" position: Shift the selector lever
down to the "–" position to select the "4" (fourth range).
Vehicles with the cruise control —
When the cruise control is being used, even if you downshift
from "D" or "5" (fifth range) to "4" (fourth range), engine
braking will not be enabled because the cruise control is not
cancelled. For vehicle speed reduction, see page 326.
Vehicles with the dynamic radar/laser cruise control —
When the cruise control is being used in the conventional
mode or in the (fixed
vehicle-to-vehicle distance control mode, even if you
downshift from "D" or "5" (fifth range) to "4" (fourth range),
engine braking will not be enabled because the cruise
control is not cancelled. For vehicle speed reduction, see
pages 356 and 341.
D Shift into the "3" (third range) position. The transmission will
downshift to third gear when the vehicle speed is or
becomes lower than 146 km/h (91 mph) and more powerful
engine braking will be enabled.
If you drive in the "D" position: Shift the selector lever to
the "S" position and shift the lever down to the "–" position
twice to select the "3" (third range). However, when you
move the lever to the "S" position while the AI shifting control
is operating, the first shift range will be "5" (fifth range), "4"
(fourth range) or "3" (third range) because the suitable shift
range is selected depending on the driving condition.
If you drive in the "S" position: Shift the selector lever
down to the "–" position to select "3" (third range).
STARTING AND DRIVING
speed) cruise control mode or in the
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