JLG 500RTS ANSI Service Manual - Manual (Page 52)

SECTION 3 - TROUBLESHOOTING
3-2 – JLG Sizzor – 3121103
Table 3-1. Platform Assembly - Troubleshooting
TROUBLE PROBABLE CAUSE REMEDY
No response to control switch
Enable switch not activated Activate enable switch
Function not activated within the 3 seconds after
enable switch was depressed Reactivate enable switch
Enable switch not functioning properly Replace enable switch circuit card
Lift control switch inoperative Repair or replace lift control switch
Hydraulic system oil low Replenish oil as necessary
No power supply See wiring diagram
Restricted or broken supply line on valve bank or
hydraulic pump Clean, repair or replace line
Control valve not functioning properly Repair or replace valve
Defective dump valve on cylinder Repair or replace dump valve
Lift cylinder not functioning properly Repair or replace lift cylinder
Hydraulic pump not functioning properly Repair or replace hydraulic pump
Platform will not raise
Enable switch not activated Activate enable switch
Function not activated within the 3 seconds after
enable switch was depressed Reactivate enable switch
Enable switch not functioning properly Replace enable switch circuit card
Load capacity exceeded. (Personnel and/or equip-
ment.) Reduce load. (Refer to capacity placard.)
Hydraulic system oil low Replenish oil as necessary
Broken or binding pivot pin Repair or replace pivot pin
Restricted or broken hydraulic line or fitting Clean, repair or replace line or fitting
Control valve not functioning properly Repair or replace control valve
Lift cylinder not functioning properly Repair or replace lift cylinder
Pump does not respond when lift control switch is
moved to the up position Refer to electrical troubleshooting table
No electrical signal being sent to lift up control valve
cartridge Refer to electrical troubleshooting table
Platform will not raise above 25 ft (7.6 m)
Leveling jacks not in contact with the ground to set
limit switches Set leveling jacks
Leveling jack limit switches not functioning prop-
erly Repair or replace limit switch
Machine is on an unlevel surface Lower platform and level machine
No power supply See wiring diagram
Platform will not lower
Enable switch not activated Activate enable switch
Function not activated within the 3 seconds after
enable switch was depressed Reactivate enable switch
Enable switch not functioning properly Replace enable switch circuit card
Pump does not respond when lift control switch is
moved to the down position Refer to electrical troubleshooting table