Page 111
34-J Desel - Servce & Parts Manual
May 2021
Secton 19 - Troubleshootng
Problem
Possible Cause
Remedy/Solution
Boom Extend/Retract
No boom extension
Excessive weight on platform
Reduce weight to within platform capacity
Level sensor out of level (platform
elevated above 10’)
Indicator light will be illuminated and alarm will sound off.
Reposition machine to level ground
Main relief valve (25) out of
adjustment
Adjust Main relief valve (25) to rated platform capacity located on function
manifold - see Hydraulic Section.
Solenoid Valve (8) (dump valve) not
energized
Check wiring to valve. Check EZ-Cal ref. P5-7 for output
Ext/Retract valve (10) not energized
Check wiring to valve. Check for EZ-Cal message or flash code.
Extend/Retract valve (10) not
shifting
Clean debris. Check for damage/replace.
Ext/Retract switch inoperative
Check switch output using EZ-Cal ref. 2D-2, P14-1 & P14-2 for upper
control digital output signal
Battery discharged - no charge
output
Check battery voltage, alternator output (14.5 volts). Check GP500 for 4-4
flash code.
System interlock
Check EZ-Cal HELP messages for interlock
Boom extends/retracts
slow
Excessive weight on Platform
Reduce weight to within platform capacity
Main relief valve (25) out of
adjustment
Adjust Extend relief valve (see Hydraulics Section) located on function
manifold.
Extend/Retract valve (10) not
shifting completely
Clean debris. Check for damage/replace.
Extend Speed adjustment reduced
in GP500 Processor
Use the EZ-Cal and check/adjust setting.
See ADJUSTMENTS/TELESCOPE OUT MAX
No boom retract
Main relief valve (25) out of
adjustment
Adjust Main relief valve (25) to rated platform capacity located on function
manifold - see Hydraulic Section.
Foreign debris stuck in boom slide
pads
Inspect/clean slide pads.
Solenoid Valve (8) (dump valve) not
energized
Check wiring to valve. Check EZ-Cal ref. P5-7 for output.
Ext/Retract valve (10) not energized
Check wiring to lift valve. Check for EZ-Cal message or flash code.
Extend/Retract valve (10) not
shifting
Clean debris. Check for damage/replace.
Ext/Retract joystick inoperative
Check joystick output using EZ-Cal ref. 2D-2, P14-1 & P14-2 for upper
control analog output signal.
Battery discharged - no charge
output
Check battery voltage, alternator output (14.5 volts). Check GP500 for 4-4
flash code.
System interlock
Check EZ-Cal HELP messages for interlock
Problem
Possible Cause
Remedy/Solution
Platform Auto-Level
Platform will not remain
level while elevating or
lowering platform (level
cylinder not moving at all)
Platform Level solenoid (4.1) valve
not energized
Check wiring to valve. Check output from GP500 P5-10 (UP) and P5-11
(DOWN).
Platform Level solenoid valve (4.1)
sticking
Remove valve and inspect for debris or damage. Replace valve located
up on the side of the boom.
Counterbalance valve faulty
Valve must not be tampered with. Replace valve.
Flow Compensator valve (2) not
shifting
Clean debris. Check for damage/replace.
Platform will not remain
level while elevating or
lowering platform (level
cylinder moving too slow
or fast)
Excessive weight on Platform
Reduce weight to within platform capacity
Main relief valve (25) out of
adjustment
Adjust main relief valve (see Hydraulics Section) located on function
manifold.
Platform Level solenoid valve (4.1)
not shifting completely
Clean debris. Check for damage/replace.
