JLG 45e Service Manual - Manual (Page 77)

SECTION 3 - TROUBLESHOOTING
3120861 – JLG Lift – 3-3
Table 3-2.BOOM ASSEMBLY - TROUBLESHOOTING
TROUBLESHOOTING CHART
TROUBLE PROBABLE CAUSE REMEDY
CONTROL VALVES.
Valve spool sticking.
Dirt in oil causing excessive temperature build-up. Flush system and change oil using recommended
viscosity
Moisture in oil. Flush system and change oil using recommended
viscosity
Incorrect valve mounting causing warping of the
unit. Loosen valve and check mounting.
Repair as necessary.
Valve spool scored. Remove valve and repair or replace as necessary.
Tie-bolts in valve over torqued. Correctly torque bolts.
Return spring weak or broken. Remove valve and repair or replace as necessary.
Relief valve malfunctioning causing excessive
pressure within valve. Check pressure delivery to and from valve and
repair or replace as necessary.
Valve leaking.
Dirt or other foreign material under seal. Remove and repair valve as necessary.
Valve spool scored. Remove valve and repair or replace as necessary.
Excessive back pressure caused by restricted
return line to reservoir. Remove line and clear obstruction or replace line
as necessary.
Damaged valve seals. Remove valve and repair or replace as necessary.
BOOM ELEVATION SYSTEM.
No response to lift control switch.
Lift control switch inoperative. Repair or replace control switch.
Lift cylinder holding valve inoperative. Repair or replace holding valve.
Dump valve (bypass) not operating. Determine cause and repair or replace valve.
Electrical malfunction. See wiring diagram.
Hydraulic system oil low. Replenish oil as necessary.
Restricted or broken supply line on valve bank or
hydraulic pump. Clean or replace line.
Control valve not functioning properly. Repair or replace valve.
Lift cylinder not functioning properly. Repair or replace cylinder.
Hydraulic pump not functioning properly. Repair or replace pump.