JLG 500RTS Service Manual - Manual (Page 53)

SECTION 3 - TROUBLESHOOTING
3120829 – JLG Sizzor – 3-3
No electrical signal being sent to lift down control
valve cartridge Refer to electrical troubleshooting table
Lift down control valve cartridge not functioning
properly Repair or replace lift down control valve cartridge
Lift cylinder not functioning properly Repair or replace lift cylinder
Platform raises and lowers erratically
Hydraulic system low Replenish hydraulic oil as required
Restricted or broken hydraulic line or fitting Clean, repair or replace line or fitting
Lack of lubricant on lift cylinder attach pins Lubricate as required (Refer to lubrication chart)
Counterbalance valve on lift cylinder improperly
adjusted or not functioning properly Replace valve
Control valve not functioning properly Repair or replace valve
Sizzor arm pins not properly lubricated Lubricate as necessary
Worn seals in lift cylinder Replace seals
Cylinder not functioning properly Repair or replace lift cylinder
Platform drifts down
Manual lowering valve not functioning properly Repair or replace valve
Worn seals in lift cylinder Replace seals
Holding valve on lift cylinder not functioning prop-
erly Repair or replace holding valve
High drive does not operate below set height
Damaged wiring on limit switch Repair or replace wiring
Damage limit switch Replace limit switch
Table 3-1. Platform Assembly - Troubleshooting
TROUBLE PROBABLE CAUSE REMEDY