SECTION 3 - TROUBLESHOOTING
3-10
– JLG Lift –
3120743
Table 3-4.Chassis Assembly - Troubleshooting
TROUBLESHOOTING CHART
TROUBLE
PROBABLE CAUSE
REMEDY
DRIVE SYSTEM.
No response to drive control.
Sevcon overheated.
Check flash code on sevcon.
Hydraulic system oil low.
Replenish oil as necessary.
Hydraulic pump not functioning properly.
Repair or replace pump.
Restricted or broken pump supply line.
Clean, repair or replace line.
Restricted or broken line on valve bank.
Clean, repair or replace line.
Drive motor(s) not functioning properly.
Repair or replace motor(s).
Damaged wiring on control switch.
Repair or replace wiring.
Control switch not functioning properly.
Replace switch. Run systems check.
Brake(s) not releasing.
Determine cause and repair or replace.
Low batteries.
Check flash code on sevcon.
Machine will not travel in forward.
Hydraulic system oil low.
Replenish oil as necessary.
Restricted or broken hydraulic line or fitting.
Clean, repair or replace line or fitting.
Control valve not functioning properly.
Repair or replace valve.
Drive motor(s) not functioning properly.
Repair or replace motor(s).
Circuit breaker open.
Determine and correct cause; reset circuit
breaker.
Brake(s) not releasing.
Determine cause and repair or replace.
Motor/Pump will not respond when DRIVE control
moved FORWARD.
Refer to Electric System Troubleshooting
Motor controller FORWARD contactor defective.
Repair or replace contactor. Run systems check.
Machine will not travel in reverse.
Motor controller REVERSE contactor defective.
See: Machine will not travel forward.
Repair or replace contactor. Run system test.
Drive system very jerky.
Sevcon controller defective.
Check flash code
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