Fiat Kobelco EX355 Tier2, Technical Manual

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EX355 T5-4-3
TROUBLESHOOTING B
• Proportional solenoid
valve is used for the ON-
OFF valve so that whether
the power boost switch is
depressed or not, as long
as an output signal from
MC is measure by means
of test harness, the control
of solenoid valve unit is
normal. If any output signal
is detected, a broken wire
harness may be a cause.
See NOTE at the end of
TABLE.
Pump Control
Pressure Sensor
Pump Delivery
Pressure Sensor
N Sensor Solenoid Valve Unit
(SG)
• To detect pump control valve
pressure in control valve to
control the travel motor swash
angle.
• To detect both right and left
pump delivery pressures to
control speed sensing system,
HP mode circuit, arm regen-
erative circuit, and travel motor
swash angle.
• To detect engine speed to
control speed sensing system.
• To increase relief setting
pressure temporarily.
• Sensor output is reduced to
zero and travel motor swash
angle is held to the maximum
angle.
• When pump delivery pressure
sensor output is 0 V or 5 V,
pump delivery pressure
sensor is monitored as
0 MPa (0 kgf/cm
2 )
• Speed sensing system does
not function.
• If solenoid valve unit (SG)
is not energized, pilot pres-
sure at port SG is 0 MPa
(0 kgf/cm
2
).
• Even if travel mode switch is
turned to the fast mode
position, travel speed does
not change to the fast
range.
• Since pump driving horse
power is calculated as 0,
pump displacement is not
controlled by speed
sensing system. Engine
may stalls in worst cases.
• HP mode does not work.
• When combined operation is
made, arm speed is slow
(when delivery pressure
sensor for pump 2 has
failed).
• Engine stalls when the
machine is operated at a high
altitude or under heavy operating
conditions.
• Main relief pressure set is
unchanged from the
standard setting pressure
of 31.4 MPa (320 kgf/cm
2
).
Even if the power boost
switch is depressed, main
relief pressure does not
increase. Digging force
does not increase.
Fault codes 04 and 05 are
displayed. Fault codes 02 and 03 are
displayed.
- -
Monitor items:
Pump 1 Control Pressure
Pump 2 Control Pressure
- Monitor item:
Actual Engine Speed (Engine
speed is not measured when N
sensor is faulty)
Monitor item:
Power boost pressure
- - - • Install test harness
(75301514). Then, check
output signal from MC and
check if harness is normal.
- - - -
• Evaluation by Dr.EX
0.25 V or Less: Discontinuity
4.75 V or More: Short Circuit
- -
T2-1 T2-1 T2-1
T2-1