SECTION 3 - TROUBLESHOOTING
3120743
– JLG Lift –
3-7
Boom extends and retracts erratically.
Hydraulic system oil low.
Replenish oil as necessary.
Wear pads worn.
Replace pads as required.
Restricted or broken hydraulic line or fitting.
Clean, repair, or replace line or fitting.
Control valve not funtioning properly.
Repair or replace control valve.
Worn seals in telescope cylinder.
Replace seals.
Cylinder not functioning properly.
Repair or replace cylinder.
Distorted boom section(s).
Replace distorted section (s).
Counterbalance valve not functioning properly.
Replace counterbalance valve.
BOOM SWING SYSTEM.
No response to swing control.
Hydraulic system oil low.
Replenish oil as necessary.
Swing control switch not functioning.
Repair or replace swing control switch.
Restricted or broken supply line on valve bank or
hydraulic pump.
Clean or replace line.
Control valve not functioning properly.
Repair or replace valve.
Swing motor not functioning properly.
Repair or replace motor.
Foreign objects (s) wedged between swing motor
pinion and swing gear.
Remove objects, check for damage, and repair or
replace component(s) as required.
No electric power to valve.
See proper wiring diagram. Run systems test.
Pressure relief valve in swing control circuit mal-
functioning.
Repair or replace reducing valve.
Restrictor valve 9s) plugged.
Clean or replace restrictor valve.
Boom will swing in only one direction.
Restricted or broken hydraulic line or fitting.
Clean, repair, or replace line or fitting.
Control valve not functioning properly.
Repair or replace valve.
Foreign object(s) wedged between swing motor
pinion and swing gear.
Remove object(s), check for damage and repair
or replace component(s) as required.
Swing joystick not functioning properly.
Repair or replace swing control switch.
Table 3-2.Boom Assembly - Troubleshooting
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