Electrohydraulic Control System - Subaru LEGACY 2002 Quick Reference Index

Automatic Transmission
2. VTD MODELS
The electrohydraulic control system for the transmission and transfer consists of various sensors
and switches, a transmission control module (TCM) and the hydraulic controlling units including
solenoid valves. The system controls the automatic transmission operation, including gear shift-
ing, lock-up clutch operation, line pressure, automatic control pattern selection ("Base" and "Pow-
er"), and gear-shift timing. It also controls operation of the transfer multi-plate clutch (LSD). The
TCM determines vehicle operating conditions from various input signals and controls a total of
eight solenoids (shift solenoids 1 and 2, low clutch timing solenoid, 2-4 brake timing solenoid, line
pressure duty solenoid, lock-up duty solenoid, transfer duty solenoid, and 2-4 brake duty solenoid)
by sending appropriate signals to them.
INPUT
Throttle position sensor
Rear vehicle speed sensor
Front vehicle speed sensor
ECM
Engine speed signal
ATF temperature sensor
Inhibitor switch
HOLD switch
ECM
Intake manifold pressure signal
Battery voltage
VDC communication
•ABS signal
•TCS signal
•VDC signal
•Steering angle
•Yaw-rate and lateral G signal
etc.
Brake switch
Torque converter turbine speed sensor
ECM
Torque control cut signal
Cruise control signal
POWER switch
Kickdown switch

ELECTROHYDRAULIC CONTROL SYSTEM

TCM
Shift solenoid 1
Shift solenoid 2
Line pressure duty solenoid
Lock-up duty solenoid
Transfer duty solenoid
2-4 brake duty solenoid
2-4 brake timing solenoid
Low clutch timing solenoid
Torque control signal 1
Torque control signal 2
AT diagnosis signal (with OBD)
AT OIL TEMP light
POWER indicator light
HOLD indicator light
Speedometer circuit
AT-8
OUTPUT
ON-OFF
ON-OFF
ECM
ECM
ECM
Combination meter
B3H2262A