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4 — MAINTENANCE
4-21
Table 4-3. Troubleshooting Chart, Continued
3. Pump motor runs, but upper
and lower boom lift func-
tions do not work.
a. Basket/ground key switch in wrong
position.
b. Boom lift out of level.
c. Outrigger not under load.
d. Hydraulic oil level low.
e. Boom enable valve solenoid SV1
failed (see item 1, Figure 6-18 or
item 4, Figure 6-19).
f. Hydraulic output filter dirty.
g. Hydraulic gear pump failed.
a. Turn key switch to enable basket or
ground controls.
b. Operate outriggers to level boom lift.
c. Check that all outriggers support a
load; adjust outriggers as needed.
d. Check hydraulic oil level per para-
graph 4-4. Add oil as needed.
e. Replace faulty wiring or solenoid.
f. Check pump output pressure, no load.
Replace filter if pump output pressure
reaches 30 psig (206 kPa gage) with
no hydraulic function selected.
g. Check pump; replace if hot to touch.
4. Pump motor runs, but the
upper and lower booms will
not retract.
a. Obstruction below basket or boom.
b. Basket/ground key switch in wrong
position.
c. Boom lift shifted out of level.
d. Outrigger not under load.
e. Hydraulic oil level low.
f. Boom enable valve solenoid SV1
failed (see item 1, Figure 6-18 or
item 4, Figure 6-19).
a. Raise and reposition the boom to
avoid the obstruction.
b. Turn key switch to ground or basket
run position.
c. If out of level alarm is sounding,
manually lower boom.
d. Check that all outriggers support a
load. If not, manually lower boom.
e. Manually lower boom. Check oil
level in reservoir; add oil as needed.
f. Manually lower boom. Repair faulty
wiring or replace failed solenoid.
5. Pump motor runs, but the
boom rotate function does
not work.
a. Basket/ground key switch in wrong
position.
b. Boom lift out of level.
c. Outrigger not under load.
d. Hydraulic oil level low.
e. Rotate obstruction or hard stop
reached.
f. Slew ring bearing worn and binding.
a. Turn key switch to ground or basket
position.
b. Operate outriggers to level boom lift.
c. Check that all outriggers are support-
ing a load; adjust as needed.
d. Check hydraulic oil level in reservoir.
Add oil as needed.
e. Rotate boom in opposite direction.
f. Retract boom and retry rotation.
Replace slew ring bearing if worn.
6. One hydraulic boom or
outrigger function fails to
work.
a. Control valve failed; leaking.
b. Cylinder counterbalance valve failed;
leaking.
c. Cylinder failed; leaking.
a. Repair or replace control valve if hot
to touch.
b. Counterbalance valves are in cylinder
manifold blocks. Repair or replace
valve if hot to touch.
c. Touch cylinder wall near piston; re-
pair or replace cylinder if hot touch.