Subaru 2002 Impreza Service Manual page 227

ELECTROHYDRAULIC CONTROL SYSTEM
Automatic Transmission
D: CONTROL ITEMS
Iescription of control
Jpshifting and downshifting are set for each range, gear
and pattern according to throttle position and vehicle speed.
2ontrol item
Base shift control
0
Base pattern
0
Power pattern
ABS-in-operation control
ATF-low-temperature con-
trol
Gear shift control
g a r is locked in 3rd when ABS signal enters.
~~
Shifting into 4th gear is prevented when ATF temperature is
Delow the preset value.
Power pattern control
Power pattern is selected when throttle opening is changed
at a speed exceeding the preset value.
When throttle opening is changed at a speed less than the
preset value, Base pattern is resumed.
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.)
Automatic pattern
select control
Base pattern control
Base lock-up control
Transmission
control
Lock-up control
Smooth lock-up is performed when lock-up is switched on. Smooth control
Ordinary control
Shifting control
Starting control
Line pressure is regulated according to throttle position,
vehicle speed and range signals.
Line pressure con-
trol
Line pressure is regulated when shifting to lessen shifting
shock.
Line pressure is lowered to a minimum so as to reduce en-
gine cranking load.
Shift step control ON/OFF timing for shift solenoid is controlled.
When shifting,-the lock-up clutch is temporarily released.
When shifting, line pressure is controlled to the optimum
level
so
as to reduce shifting shock.
Transfer clutch pressure is regulated according to the
throttle valve angle and vehicle speed.
Transfer clutch pressure is increased.
Immediately after detecting a slip, transfer clutch pressure is
controlled to the same pressure as 1 range. (This control is
canceled if V 2 60 km/h (37 MPH), or when throttle valve is
closed fully.)
Lock-up controt
Shift timing control
Line pressure control
Ordinary transfer control
1 range control
AWD transfer
clutch control
(non-turbo
model)
Slip control
Transfer clutch pressure is reduced after detecting a turn.
Control in turns
Transfer clutch pressure is adjusted to a set level immedi-
ately after reception of ABS signal.
ABS-in-operation control
Multi-plate clutch (LSD) pressure is regulated according to
the torque input to the transfer and the driving condition.
Ordinary transfer control
When starting, the LSD pressure is adjusted proportionately
to the throttle value angle.
When the front and rear wheel speed ratio is less than the
set value for a vehicle speed, the LSD pressure is de-
creased.
Start control
Control in turns
AWD multi-
plate clutch
control (LSD)
(turbo model)
When a front or rear wheel starts slipping, the LSD pressure
is decreased.
The LSD pressure is adjusted to the set level immediately
after reception of ABS signal.
When the brake switch is ON and throttle valve is fully
closed, the LSD pressure is lowered.
The LSD pressure is increased to improve driveability.
Slip control
ABS-in-operation control
Base brake control
1 range control
AT-5