TM 5-3895-373-20
2.19.
HYDRAULIC SYSTEM DIAGNOSTICS.
Perform hydraulic system tests whenever you have a
problem with the hydraulic system or if sent here by
another diagnostic test.
Most of the paving machine’s hydraulic functions share
pumping and flow control components with at least one
other circuit. Try to determine which hydraulic function is
most affected by the fault condition. Refer to the index
below for the diagnostic procedure that applies to your
system fault.
Hydraulic systems can be hazardous. Always heed the
following warnings when troubleshooting or servicing
components in the hydraulic system.
Hydraulic oil under pressure can
penetrate skin or damage eyes. Oil
leaks under pressure may not be
visible. Use apiece of cardboard or
wood to find leaks, but do not use a
bare hand. Wear safety goggles for
protection. If oil enters skin or eye,
get immediate medical attention.
Do not move under any hydraulically
controlled component when making
adjustments
or
repairs
to
the
hydraulic
system.
Lower
the
component and work from above. If
the component must be raised for
access,
always
block
it
for
full
support. If a component drops,
severe injury or death to personnel
can result.
NOTE
Throughout
these
hydraulic
systems
diagnostic
procedures, the engine should be running at high idle
when performing a functional check of a hydraulic device
or circuit.
When diagnosing hydraulic devices that are controlled
through the stack valve, references will be made to the
stack valve wiring diagram on page 2-265.
When a fault is isolated to a specific component, the
paragraph number of the repair task for replacement of
the component is cited in the diagnostic flowchart. If the
repair task is general (i.e.: wiring and harness repair), the
repair task is cited in the Reference Information Column.
Male connectors on paving machine most often house
female terminals (receptacles, jacks). Mating female
connectors house male terminals (plugs). Plug/jack
nomenclature in text and diagrams is based on nature of
connector terminals (male or female), not on appearance
of connector housing.
Refer to TM 5-3895-373-10 for paving machine switch
locations.
Throughout
this
diagnostic
procedure,
a
simplified
schematic of the circuit under test is shown. Reference
electrical schematics at back of manual for complete
circuit wiring.
Diagnostic Index
Fault Location
Page
Hydraulic Cylinder Circuits ................................... 2-264
Auger/Conveyor Circuit ........................................ 2-306
Screed Vibrator Circuit ......................................... 2-324
2-263
