Mec 4069RT - Page 119

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