JLG 40H Service Manual - Manual (Page 127)

SECTION 3 - TROUBLESHOOTING
3120240 – JLG Lift –
3-15
Function sluggish during operation.
(System pressure too low.) Main relief valve set too low.
Pump section not delivering sufficient oil.
Main relief valve stuck in open position.
Oil viscosity too low.
Leak in component, line or fitting.
Scored valve spool; scored cylinder.
Amperage too low on controller.
Low sequence pressure.
Low pilot pressure.
Wrong/defective spool in drive section.
Low voltage in electrical system.
Reset valve as required.
Repair or replace pump section or pump.
Clean, repair, or replace valve.
(Check system oil for contamination)
Drain system and replace with recommended oil.
(Refer to Hydraulic Oils.)
Repair or replace component, line or fitting.
Replace valve; replace cylinder.
Correctly adjust controller.
Reset valve as required.
Reset valve as required.
Repair or replace drive section.
Correct low voltage problem.
System(s) operate erratically. Sticking or binding valve spool, pistons, rods, etc. Clean, repair, or replace components as required.
AUXILIARY HYDRAULIC SYSTEM.
Auxiliary hydraulic pump inoperable. Circuit breaker open.
Check valve in system leaking.
Battery requires charging or will not hold a charge.
Damaged wiring on control switch or auxiliary pump.
Control switch not functioning properly.
Restricted or broken hydraulic line or fitting.
Pump motor solenoid not functioning properly.
Pump motor not functioning properly.
Low pilot pressure.
Determine and correct cause; reset circuit breaker.
Repair or replace valve.
Charge or replace battery as required.
See proper wiring diagram.
Replace switch.
Clean, repair, or replace line or fitting.
Replace solenoid.
Repair or replace motor.
Reset valve as required.
TROUBLE PROBABLE CAUSE REMEDY
HYDRAULIC SYSTEM - GENERAL.