JLG 120HX ANSI Service Manual - Manual (Page 97)

SECTION 3 - TROUBLESHOOTING
3120686 – JLG Lift – 3-15
If equipped, swivel coupling leaking internally.
(Seals defective.) Repair or replace coupling.
Steer control valve not functioning properly. Repair or replace valve.
Steer cylinder not functioning properly. Repair or replace cylinder.
Machine hard to steer or steering is erratic.
Hydraulic system oil low. Replenish oil as necessary.
Restricted hydraulic line or fitting. Clean, repair or replace line or fitting.
Restricted crossover relief valve. Clean or replace valve.
Steer system pressure low. Adjust pressure.
Bent linkage (tie rods). Repair or replace linkage as required.
Hydraulic pump not functioning properly. Repair or replace pump.
Steer cylinder not functioning properly. Repair or replace cylinder.
Steering inoperative.
Damaged wiring on control switch or solenoid
valve. See proper wiring diagram.
Solenoid valve not functioning properly. Repair or replace valve.
Control switch not functioning properly. Replace switch.
Relief valve improperly set or not functioning
properly. Reset, repair or replace valves as required.
Steer cylinder not functioning properly. Repair or replace cylinder.
Machine will not steer left or to the right.
Wiring on control switch is damaged. See proper wiring diagram.
Wiring on solenoid valve damaged. Repair or replace wiring.
Coil in solenoid damaged. Replace coil.
No oil flow or pressure to steer circuit. Take pressure reading at steer valve and adjust
as necessary.
Bent cylinder rod. Repair or replace cylinder.
Damaged tie rod. Replace tie rod.
Crossover relief valve sticking. Repair crossover relief valve.
Cylinder packing defective. Repair or replace cylinder.
Table 3-4.Chassis Assembly - Troubleshooting
TROUBLE PROBABLE CAUSE REMEDY