TM 5-3805-281-24-1
Diagnostic Information
Part Name
Engine and Pump
Front and Rear Pump
Flow Combiner Valve
Arm I Power Passage
Controller (EPC)
Control Valve
Check Valve and
Restriction Orifice
Operational
To control engine speed,
To send a regulated pilot
To supply oil to left and
To ensure there is enough
Function
pump and valve operations.
pressure signal to pump
right propel spools during
oil flow to the swing
regulators in responds to
combined operation of dig
function when used in
the flow rate through
and propel functions.
combined operation with
neutral passages in control
arm function.
valve.
Control Problems
Problems may differ
Pressure signal to pump
Sticking or stuck spool. Oil
Oil from left control valve
depending on the
regulator does not increase
is insufficient or not
power passage insufficient
malfunction.
when a function is actuated.
supplied to left propel
or not supplied to arm I
Pump stays at minimum
spool.
spool.
flow.
Machine Symptoms
Problems listed indicate
For rear pump control
While traveling straight,
Arm speed slow when
malfunction in EPC. With
valve: left propel cycle time
machine mistracks when
key switch on, EC motor
slow, swing also slow; cycle
swing is actuated.
does not go to slow idle
time for bucket, boom or
position; engine starts and
arm almost normal. For
run at slow idle. Engine
front pump control valve:
speed cannot be increased.
bucket cycle time very slow,
Pump stays at minimum, all
boom not raised when
functions are slow.
time slow; cycle time for
boom, arm, or swing almost
normal.
Laptop Computer
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Self-Diagnostic
Functions
Laptop Computer
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Monitor No. 1, Front pump
--
9025
Monitoring Function
control pressure and No. 6,
15
Rear pump control
7
pressure.
Harness Check
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Notes
Check fuses before
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replacing EPC.
Description of
See Engine and Pump
See Pump Control Valve
See Flow Combiner Valve
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Operation.
Controller Circuit Theory of
Operation in Group
Operation in Group
Operation in Group
9025-05.
9025-05.
9015-15.
Continued on next page
CED,TX08227,3177
1904JUN986/9
6-114