Subaru 2002 Impreza Service Manual page 225

ELECTROHYDRAULIC CONTROL SYSTEM
Automatic Transmission
B: INPUT SIGNALS
Signal name
Throttle position sensor
Front vehicle speed sensor
(located on transmission case)
Rear vehicle speed sensor
(located on extension case)
Engine speed signal
Inhibitor switch
ATF temperature sensor
FWD switch (non-turbo model)
ABS signal
Cruise control signal
Torque converter turbine speed sensor
Torque control cut signal
. .
.
Intake manifold pressure signal
(non-turbo model)
Mass air flow signal (turbo model)
Brake switch
Major function
Indicates the throttle valve position. This signal is used to determine shift point, line
pressure, and lock-up engaging vehicle speed, which vary with engine load.
Indicates the vehicle speed. This signal is used for control of gear shifting, lock-up
engaging, line pressure, and transfer clutch operation.
Used to control transfer clutch, and also as backup signal in case of failure of front
vehicle speed sensor.
Indicates the engine speed. This signal is used for control of lock-up clutch to en-
sure smooth engagement.
Used to determine gears and line pressures in each of ranges "P", "R", "N", "D",
"399, "2"
and
"1
3 3 ,
Indicates the ATF temperature. This signal is used for inhibition of lock-up, release
of OD and determination of ATF temperature.
Used to change the mode from AWD to FWD. Also used to adapt the vehicle to
FWD tester roller. Changeover from AWD to FWD can be made by inserting a fuse
into the fuse holder.
Used when ABS is operating to optimize ABS control. In this control, transfer
clutch torque load capacity is adjusted to eliminate the influence of engine braking
and reduce the degree
o f
coupling between front and rear wheels.
Indicates operation of cruise control system. It is used to expand "4th" operating
range.
Tells the rotation speed of the input shaft. The proportion of this speed to the ve-
hicle speed determines whether shifting should be made or not.
Sent from engine control module (ECM) to TCM to inhibit the torque control.
Used to determine line pressure of gear shifting.
Used to determine line pressure of gear shifting.
If this signal is issued during downhill driving, TCM makes shift down control,
causing the vehicle speed to be reduced.
AT-3