Automatic Transmission
ELECTROHYDRAULIC CONTROL SYSTEM
AT-12
2. VTD MODELS
Control item Description of control
Transmission
control
Gear shift control Base shift control
! Base pattern
! Power pattern
Upshifting and downshifting are set for each range, gear and
pattern according to throttle position and vehicle speed.
ABS-in-operation control Gear is locked in 3rd when ABS signal enters.
ATF low temperature con-
trol
Shifting into 4th gear is prevented when ATF temperature is
below the preset value.
Hold control With HOLD switch ON, vehicle starts in 2nd gear (if the D, 3
or 2 range is selected).
Power pattern control
(POWER light ON)
Power pattern is selected when POWER switch is ON.
Base pattern control
(POWER light OFF)
Base pattern is selected when POWER switch is OFF.
Lock-up control Base lock-up control Lock-up ON is set for D-range 4th gear; ON/OFF is set for all
gears (except D-range 4th) and patterns. Lock-up control is
performed according to throttle position and vehicle speed.
(Basically lock-up is OFF during gear shifting.)
Smooth control Smooth lock-up is performed when lock-up is switched on.
Line pressure con-
trol
Ordinary control Line pressure is regulated according to throttle position, vehi-
cle speed and range signals.
Shifting control Line pressure is regulated when shifting to lessen shifting
shock.
Starting control Line pressure is lowered to a minimum so as to reduce en-
gine cranking load.
Shift timing control Shift step control ON/OFF timing for shift solenoid is controlled.
Lock-up control When shifting, the lock-up clutch is temporarily released.
Line pressure control When shifting, line pressure is controlled to the optimum level
so as to reduce shifting shock.
AWD mult-
plate clutch
control (LSD)
Ordinary transfer control Multi-plate clutch (LSD) pressure is regulated according to
the torque input to the transfer and the driving condition.
Start control When starting, the LSD pressure is adjusted proportionately
to the throttle value angle.
Control in turns When the front and rear wheel speed ratio is less than the set
value for a vehicle speed, the LSD pressure is decreased.
Slip control When a front or rear wheel starts slipping, the LSD pressure
is decreased.
ABS-in-operation control The LSD pressure is adjusted to the set level immediately af-
ter reception of ABS signal.
Base brake control When the brake switch is ON and throttle valve is fully closed,
the LSD pressure is lowered.
1 range control The LSD pressure is increased to improve driveability.
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