Platform assembly - troubleshooting -2 – JLG M450 ANSI Service Manual User Manual
Page 216
SECTION 7 - BASIC TROUBLESHOOTING, ELECTRICAL INFORMATION, & SCHEMATICS
7-2
– JLG Lift –
3121127
.
Table 7-1. Platform Assembly - Troubleshooting
TROUBLE
PROBABLE CAUSE
REMEDY
Automatic leveling inoperative.
Hydraulic system oil low.
Replenish oil as necessary.
Dual check valves dirty/inoperative.
Clean or replace as necessary.
Restricted or broken hydraulic line or fitting on
slave cylinder or main lift cylinder.
Clean, repair, or replace line or fitting.
Worn seal(s) in slave level or main lift cylinder.
Replace seal(s).
Counterbalance valve in slave cylinder defec-
tive.
Replace counterbalance valve.
Slave level or main lift cylinder not functioning
properly.
Slave level or main lift cylinder not functioning
properly.
Platform will not maintain level attitude.
Counterbalance valve on slave leveling cylinder
improperly adjusted or not functioning properly.
Replace valve.
Worn seal(s) in slave level or main lift cylinder.
Replace seal(s).
Damaged slave level or main lift cylinder.
Repair or replace cylinder.
No response to platform leveling controls.
Level function not activated within 7 seconds
after footswitch was depressed.
Recycle footswitch.
Level control switch inoperative.
Repair or replace control switch lever.
Hydraulic system oil low.
Replenish oil as necessary.
Proportional Flow Regulator not powered.
Wiring: Run System Test
Restricted or broken hydraulic line or fitting.
Clean, repair, or replace line or fitting.
Directional valve not functioning properly.
Repair or replace valve.
No electric power to directional control valve.
See proper wiring diagram/Run System Test.
Slave cylinder not functioning properly.
Repair or replace pump.
Platform will not adjust "up" or "down" to level.
Hydraulic pump not functioning properly.
Run System Test.
Restricted or broken hydraulic line or fitting.
Clean, repair, or replace line or fitting.
Slave cylinder not functioning properly.
Repair or replace cylinder.
Electrical failure.
See proper wiring diagram/Run System Test.
Orifice plugged.
Clean orifice.