JLG 450A Service And Maintenance Manual page 95

TROUBLE
No response to control.
Machine will not travel in forward.
3120869
Table 3-4.Chassis Assembly - Troubleshooting
PROBABLE CAUSE
Drive wheel tire treads worn smooth.
Drive brakes "dragging".
System pressure too low.
Drive hub(s) defective.
Engine RPM's not set.
Drive motors worn.
Counterbalance valve defective.
Low amperage on controller.
DRIVE SYSTEM.
Drive function not activated within 7 seconds
after footswitch was depressed.
Hydraulic system oil low.
Hydraulic pump not functioning properly.
Restricted or broken pump supply line.
Restricted or broken line on valve bank.
Drive motor(s) not functioning properly.
Air in wheel brake circuit.
Fuse is blow-out on control card.
Damaged wiring on control switch.
Control switch not functioning properly.
Brake(s) not releasing.
Hydraulic system oil low.
Restricted or broken hydraulic line or fitting.
Control valve not functioning properly.
Drive motor(s) not functioning properly.
Circuit breaker open.
Counterbalance valve sticking on return side.
– JLG Lift –
SECTION 3 - TROUBLESHOOTING
REMEDY
Replace tires as necessary and inflate to speci-
fied pressure.
Re-adjust pressure.
Re-adjust pressure.
Repair or replace hub.
Correctly set engine RPM.
Repair or replace drive motors.
Replace counterbalance valve.
Correctly adjust controller.
Recycle footswitch.
Replenish oil as necessary.
Repair or replace pump.
Clean, repair or replace line.
Clean, repair or replace line.
Repair or replace motor(s).
Bleed circuit, determine and correct cause.
Replace fuse.
Repair or replace wiring.
Replace switch.
Determine cause and repair or replace.
Replenish oil as necessary.
Clean, repair or replace line or fitting.
Repair or replace valve.
Repair or replace motor(s).
Determine and correct cause; reset circuit
breaker.
Adjust return counterbalance out 3 turns - cycle
drive - return to original position.
3-11