Komatsu Galeo PC138US-8, Shop Manual

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SEN02465-01 40 Troubleshooting
14
PC138US, USLC-8
Failure code [DHPAMA] Pump press sensor abnormality 1
User code Failure code
Trouble
Pump pressure sensor abnormality
(Pump controller system)
— DHPAMA
Contents of
trouble
• Signal voltage of pump pressure sensor circuit is below 0.3 V or above 4.4 V.
Action of
controller
• Fixes pump pressure at 0 MPa {0 kg/cm
2
} and continues control.
• If cause of failure disappears, system resets itself.
Problem that
appears on
machine
• Automatic gear shifting function does not work.
• Straight travel performance or steering performance lowers.
Related
information
a
If 5V circuit (3) and ground circuit (1) of pressure sensor are connected inversely, pressure sensor
will be broken. Accordingly, take extreme care when checking.
• Pump pressure can be checked with monitoring function. (Code: 01100 Pump pressure)
• Method of reproducing failure code: Turn starting switch ON or start engine.
Possible causes
and standard
value in normal
state
Cause Standard value in normal state/Remarks on troubleshooting
1
Defective 5V sensor power
supply 1 system
a
If failure code [ DA25KP ] is also displayed, carry out trouble-
shooting for it first.
2
Defective pump pressure
sensor (Internal defect)
a
Prepare with starting switch OFF, then turn starting switch ON
or start engine and carry out troubleshooting in each case.
P25 Voltage
Between (3) – (1) Power supply 4.5 – 5.5 V
Between (2) – (1) Signal 0.3 – 4.5 V
If voltage is abnormal, check failure code. (If "E" of failure code
goes off at this time, pump pressure sensor is defective.)
3
Disconnection in wiring har-
ness (Disconnection in wiring
or defective contact in con-
nector)
a
Prepare with starting switch OFF, then carry out troubleshoot-
ing without turning starting switch ON.
Wiring harness between C01 (female) (18)
– P25 (female) (1) Resis-
tance
Max. 1
z
Wiring harness between C01 (female) (49)
– P25 (female) (2) Resis-
tance
Max. 1
z
Wiring harness between C01 (female) (9) –
J07 – P25 (female) (3) Resis-
tance
Max. 1
z
4
Ground fault in wiring har-
ness (Short circuit with GND
circuit)
a
Prepare with starting switch OFF, then carry out troubleshoot-
ing without turning starting switch ON.
Wiring harness between C01 (female) (49)
– P25 (female) (2) Resis-
tance
Min. 1 M
z
5
Hot short (Short circuit with
24V circuit) in wiring harness
a
Prepare with starting switch OFF, then turn starting switch ON
and carry out troubleshooting.
Wiring harness between C01 (female) (49)
– P25 (female) (2)
Voltage Max. 1 V
6 Defective pump controller
If causes 1 – 5 are not detected, pump controller may be defective.
(Since trouble is in system, troubleshooting cannot be carried out.)