Mec 4069RT Service And Parts Manual page 119

Table 4-1: Troubleshooting Chart
PROBLEM
Platform will not lower Maintenance lock in maintenance position Return maintenance lock to the stowed position
or lowers slowly
Lowering valve not energized
Lowering valve not shifting
Lowering orifice/s plugged
System interruption
Lowers but not Down valve on lift cylinder inoperative
completely
Emergency lowering Lowering valve not shifting
not working
Lowering orifice plugged
Valve coil failed on cylinder
Drive
No drive function Lift/Drive select switch not in Drive
position or not operational
Drive valve not shifting
Proportional Valve not shifting
Drive system shut down (interlock)
No drive elevated Unit out of level
System Interruption (interlock)
Slow drive with High torque enabled
platform stowed
Malfunctioning rear wheel bypass valve
Wheel motors not functioning correctly
Poor gradeability or High or mid speed enabled
drive performance
Batteries discharged
Wheel motors not functioning correctly
Malfunctioning rear wheel bypass valve
Malfunctioning series parallel valves
Incorrectly adjusted or worn hydraulic
pump
Drive in one direction Drive valve not energized in one direction
only
Counterbalance valve CBV1 or CBV2 not
functioning correctly
No output from GP400
POSSIBLE CAUSE
"4069RT" Service and Parts Manual
T - - T
R O U B L E S H O O T I N G
REMEDY/SOLUTION
Check wiring to lowering valve located on Lift Cylinder
Clean debris, check for damage, replace
Clean orifice/s located inside hose fitting on lift cylinder
Check HELP messages using EZ-cal
Check lift valve coil
Clean debris, check for damage, replace
Clean orifice/s located inside hose fitting on the lift cylinder
Test (6-8 ohms), replace
Select Drive position (upper control box), Check switch
Check switch position from GP400 with EZ-cal
DLD
Check connections at valve
Check Drive Valve for contamination
Check Drive output from GP400 (
Check connections at valve
Check Proportional valve for contamination
Check proportional output from GP400
Check HELP and MODE message on EZ-Cal
Lower and operate Auto-level
Check HELP messages using EZ-Cal
Check Speed/Torque switch on upper controls
Located on rear wheel motors only
Check electrical by disconnecting valves
Check function by replacing valves
Inspect wheel motors for excessive bypass
Check Speed/Torque switch on upper controls
Check battery voltage with multi-meter or EZ-Cal
Clean, service, charge batteries
Inspect wheel motors for excessive bypass
Located on rear wheels only
Check electrical by disconnecting valves
Check function by replacing valves
Located on top of main hydraulic manifold
Remove and inspect
See Hydraulics section for pump adjustment
Inspect or replace pump
Check 12 volts to appropriate coil
Check coil
Check valve function
Swap counterbalance valves to see if functioning direction
changes
Check switch position output from GP400
C
R O U B L E S H O O T I N G H A R T
March 2014
Page 4-23