Lexus GX460 Manual page 192

2-1. Driving procedures
S mode
■
When the shift range is 5 or lower, holding the shift lever toward "+" sets the shift
range to 6.
AI-SHIFT
■
AI-SHIFT automatically selects the optimal gear according to driver performance
and driving conditions.
AI-SHIFT automatically operates when the shift lever is in the D position. (Shifting
the shift lever to the S position cancels the function.)
When driving with the cruise control or dynamic radar cruise control
■
Engine braking will not occur in S mode, even when downshifting to 5 or 4. 
(P. 244, 248)
If the shift lever cannot be shifted from P
■
P. 740
If the "S" indicator does not come on even after shifting the shift lever to S
■
This may indicate a malfunction in the automatic transmission system. Have the
vehicle inspected by Lexus dealer immediately.
(In this situation, the transmission will operate in the same manner as when the shift
lever is in D.)
Downshift restriction warning buzzer (S mode)
■
To help ensure safety and driving performance, downshifting operation may some-
times be restricted. In some circumstances, downshifting may not be possible even
when the shift lever is operated. (A buzzer will sound twice.)
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GX460_U.S.A. (OM60G24U)