Mitsubishi Eclipse. Technical Information Manual (1994) — part 68
A B S
ACTUATOR
HYDRAULIC UNIT (HU)
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The HU, elastically supported by the shield plate
at the front left of the engine compartment, con-
sists of a motor pump, plunger valve, reservoir
and three solenoid valves.
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The HU, positioned between the brake master
cylinder and each wheel cylinder, is a hydraulic
circuit split into two systems associated with
the normal X pipings when the ABS is inactive.
the wheel cylinder.
When the ABS is active, the motor is operated
by a signal from the ABS-ECU to let the pump
generate a hydraulic pressure required to return
fluid against master cylinder pressure. At the
same time, three solenoid valves are operated
to control the hydraulic pressure that acts on
Solenoi
14x0305
Hydraulic unit
Wheel speed sensor
Master cylinder
Solenoid valve and select-low valve
Refer to 1991 3000GT Technical Information Manual
(Pub. No.
Relay box
Refer to P. 3-33.
MOTOR RELAY
Refer to P. 3-33.
VALVE RELAY
Refer to 3-33.
ABS WARNING LIGHT
Refer to P. 3-33.
DRIVE-CONTROL COMPONENTS ABS
ELECTRONIC CONTROL UNIT (ECU)
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The ABS-ECU detects the vehicle speed in
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The ABS-ECU has diagnostic and memory
terms of a signal from the wheel speed sensor
tions.
to determine the rotating condition of the wheel,
If any failure is found, the fail-safe function is
estimates the skidding condition of the wheel
activated and the ABS warning light will
on the basis of the predetermined theory, and
nate.
outputs a signal to move the solenoid valve
in the HU in such a way as to prevent locking
the wheel.
BLOCK DIAGRAM
ABS-ECU
Battery I--
r
-
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Wheel speed
sensors
Sensor
interface
circuit
r
CPU monitor circuit
Motor, solenoid control,
monitor circuit
Valve relay
drive circuit
I
interface circuit
FUNCTION OF INDIVIDUAL CIRCUITS
The function of each circuit is the same as in the
FWD vehicle. (Refer to P. 3-35.)
Motor-relay
V a l v e r e l a y
ABS
EXPLANATION OF ECU CONTROL
Braking Hydraulic Pressure Control
Braking hydraulic pressure control is the same as
in the FWD vehicle. (Refer to P. 3-36.)
Control
ABS on AWD models controls the front and rear
wheels using select-low and activates the solenoid
wheels are controlled mechanically in select-low
valve on one side, including either of the front
by the select-low valve, there is, as a result, pressure
wheels. Furthermore, since the rear right and left
control of three wheels (either front wheel and the
rear right and left wheels) at a time.
FL wheel
FR wheel
Select-
1
Select-
low
RL wheel
wheel
Select-low valve
Control Speed
The control speed is the same as in the FWD vehicle.
(Refer to P. 3-36.)
ABS
Control with G-sensor
Since four wheels are connected in AWD models,
and a high frictional resistance road and makes
the four wheels may decelerate almost in phase.
This tendency is especially strong on a low frictional
resistance road; suspected vehicle speed does not
match actual speed, the road is judged to be a
high frictional resistance road and the ABS control
becomes unreliable. At such a time, the G-sensor
distinguishes* between low frictional resistance road
the ABS control reliable by switching the method
of calculating suspected vehicle speed.
When braking on a low frictional resistance road,
the rate of vehicle deceleration is slow. On the
other hand, when braking on a high frictional
resistance road, the rate of vehicle deceleration
is fast.
Warning
light
Approx.
1 sec.
Approx.
1 sec.
ABS Warning Light Control
In the following cases the ABS warning light lights up.
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It lights up when trouble in the system is recognized.
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It illuminates in the pattern shown in the figure on the
left when the ignition switch is turned ON, to check the
ABS warning light circuit.
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