Subaru XT 1988 Service Manual page 851

STEERING SYSTEM 4-3
Electronic- Controlled Moter
Drive Power Steering
System Configuration
The electronic-controlled motor drive power steering system
detects both car speed and frequency of steering operation. It
activates the motor to supply the required amount of oil to
the gear box through a command from the controller and pro-
vides "assist" force in relation to car speed.
Signal
controller t - - - - - - - ,
Ignition switch
In other words, this system is a car-speed sensing type which
reduces "assist" force as car speed increases. It automatically
selects four driving modes according to average car speed and
frequency of steering operation.
These modes include high-speed driving, suburban driving,
winding-road driving and city-driving. The motor will not
activate when not steering at car speeds below 10 km/h (6
MPH).
+
Battery
Alternator
Engine
Pump driven by
electric motor
Speed sensor
Sensor steering
Power steering gearbox
L4·1401
Fig. 4
5