JLG M400 Service Manual Service Manual User Manual
Page 230
SECTION 7 - BASIC TROUBLESHOOTING, ELECTRICAL INFORMATION, & SCHEMATICS
7-16
– JLG Lift –
3121827
Function sluggish during operation. (System
pressure too low.)
Main relief valve set too low.
Reset valve as required.
Pump section not delivering sufficient oil.
Repair or replace pump section or pump.
Main relief valve stuck in open position.
Clean, repair, or replace valve. (Check system oil
for contamination.)
Oil viscosity too low.
Drain system and replace with recommended oil.
(Refer to Hydraulic Oils.)
Leak in component, line or fitting.
Repair or replace component, line or fitting.
Scored valve spool; scored cylinder.
Replace valve; replace cylinder.
Hydraulic Filter clogged.
Replace filter.
Amperage too low on controller.
Correctly adjust controller.
Low voltage in electrical system.
Correct low voltage problem.
System(s) operate erratically.
Sticking or binding valve spools, pistons.
Clean, repair, or replace components as
required.
Table 7-5. Hydraulic System - Troubleshooting
TROUBLE
PROBABLE CAUSE
REMEDY