Subaru XT 1988 Service Manual page 572

3-2 AUTOMATIC TRANSMISSION AND DIFFERENTIAL
2) MAJOR COMPONENTS AND THEIR FUNCTIONS
Component name
Function
Sensor Throttle opening sensor
Detects throttle opening. This signal is used for determining the transfer
oil pressure.
Battery voltage
Detects battery voltage. Used for voltage compensation of duty solenoid.
ATF temperature sensor
Detects ATF temperature. Used for temperature compensation of duty
solenoid.
Vehicle revolution sensor 1 Detects rear-wheel speed. 30 pulses are generated per rotation of propeller
shaft. This signal is used for determining the transfer oil pressure.
Vehicle revolution sensor 2
Detects front-wheel speed. Four pulses are generated per rotation of
speedometer cable. Th is signal is used for determining the transfer oil
pressure.
Inhibitor switch
Detects selected range signal. Used for determining the transfer oil
pressure.
Idle switch
Used to release control when "slip" is detected.
Forced FWD switch Detects FWD mode. Releases transfer clutch.
1st hold switch When 1st hold range is selected increases the transfer oil pressure.
Actuator Duty solenoid C
This solenoid is operated
by
a signal sent from transmission control unit
with duty ratio of 5 to 95% at driving frequency of 50 Hz. This solenoid
controls the transfer clutch hydraulic pressure.
Transmission control unit
Computes the duty ratio according to signals sent from various sensors,
and issues a signal to the duty solenoid for driving.
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