Subaru XT 1988 Service Manual page 853

STEERING SYSTEM
4-3
2) Normal processing
Upon completion of the initial diagnosis, normal processing
controls steering in response to car speed and steering fre-
quency.
(1) Diagnosis and fail-safe function
The operation of the signal controller, power controller,
signal system and motor power supply is monitored at all
times. If a problem occurs, the warning lamp (located in
the combination meter) comes on to warn the driver. The
fail-safe function activates, depending on the type of
problem, and current flow to the motor is controlled to
maintain proper steering.
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Warning lamp
L4-1403
Fig. 6
(2) The following functional checks are conducted con-
stantly during normal processing.
CD
When current in excess of 100 A flows to the
motor for more than 10 seconds, the warning lamp
comes on. "Duty" will then decrease to "0."
®
When power supply greater than 9 V continues
for at least 1 second, the warning lamp comes on.
"Duty*! " will gradually decrease. When the normal
power supply is restored, the warning lamp goes out.
"Duty" will then be controlled.
@
When the engine stops, the warning lamp comes
on. "Duty*
1"
will then gradually decrease. After
restarting, the warning lamp goes out. "Duty" will be
controlled again.
@
If no pulses are emitted when speed exceeds 25
km/h (16 MPH), the car-speed sensor system will
register a "malfunction". The steering force im-
mediately before the malfunction is maintained.
*1: Refers to a "relaxation" function (when is OFF).
(3) Relaxation function for changes in driving modes
"Duty" differs with driving modes. If "Duty" changes
abruptly in response to a change in driving mode, a shock
is felt on the steering wheel. To prevent this, "Duty" is
gradually decreased by 1 degree every 0.1 seconds*2.
7
(4) Assist control function
Q)
Car speed greater than 10 km/h (6 MPH)
"Duty" is determined by both car speed and driving
mode.
®
Car speed less than 10 km/h (6 MPH)
When a steering pulse is entered, "Duty" will be
100%. If no pulse (for steering) is entered thereafter,
"Duty" will decrease gradually.
(5) Relaxation function (when is OFF)
A great shock will be felt on the steering wheel if "Duty"
is abruptly decreased to "0". The "Duty" is decreased by
1 degree every 0.5 seconds*2.
*2: 1 deg.
=
(2.5 to 3.5%)
3) Other functions
(1) Sub-fan control
When the steering wheel is turned very quickly at speeds
below 10 km/h (6 MPH), the sub fan is turns OFF.
When speed increases to 10 km/h (6 MPH) and the steer-
ing wheel is turned slowly, the sub fan comes ON again.
(2) "Runaway" detection function
When the microcomputer runs away of if the internal
power supply drops below the specified voltage, the
microcomputer will reset*3.
*3: Refers to restoration of the microcomputer to a state
in which the power is initially turned ON.
System Check Mode
1) Self-check procedures
Ignition OFF
Connect check terminal to GND.
Start the engine.
Drive the car at least 10 meters (33 ft.)
Turn steering wheel at least 90
0
•
Wait for 15 seconds.
Disconnect check terminal from GND.