Page 113
34-J Desel - Servce & Parts Manual
May 2021
Secton 19 - Troubleshootng
Problem
Possible Cause
Remedy/Solution
Drive
No drive operation
Planetary hub bypass engaged
Check bypass plates located in the center of each planetary hub. Should
be convex. Turn over if not.
System interlock
Check EZ-Cal HELP messages for interlock
Hydraulic oil incorrect for severe
low temperatures
Use hydraulic tank warmer if equipped. Operate drive continuously until
drive begins to operate.
Problem
Possible Cause
Remedy/Solution
Drive
No drive operation
Drive Valve (on drive pump) not
energized
Check Drive output from GP500 2Fl, P4-2 (FWD) and P4-3 (REV).
Check for power at valve coils located on top of the drive pump.
Drive Valve (on drive pump) not
shifting
Check drive valve for contamination
Brakes not releasing (system under
pressure when drive attempted)
Check brake valve and brake pressure. See hydraulic diagram for
location.
Drive joystick output failure
Check drive joystick output from GP500 (see 2E2, P10-1) check joystick
enable trigger operation, Check wire connections.
Low pump charge pressure
Check at brake manifold port GCP (see hydraulic Diagram).
Adjust stand-by pressure to 300 PSI (21 bar).
Incorrectly adjusted or worn
hydraulic drive pump
See Hydraulics Section for pump adjustment. Inspect or replace pump.
No drive with platform
elevated
Unit out of level
Lower boom and operate on more level surfaces.
FWD MIN, REV MIN setting
incorrect
Reset drive speeds using EZ-Cal
Hydraulic oil incorrect for severe
low temperatures
Use hydraulic tank warmer if equipped. Operate drive continuously until
drive begins to operate.
Low pump charge pressure
Check at brake manifold port GCP (see hydraulic Diagram).
Adjust stand-by pressure to 300 PSI (21 bar).
System interlock
Check EZ-Cal HELP messages for interlock
**CE rated models
Axles not parallel
Reposition machine on flat ground
Slow drive with platform in
stowed position and boom
retracted
Slow engine RPM.
Check throttle solenoid.
Hydraulic oil incorrect for severe
low temperatures
Use hydraulic tank warmer if equipped. Operate drive continuously until
drive begins to operate.
Low pump charge pressure
Check at brake manifold port GCP (see hydraulic Diagram).
Adjust stand-by pressure to 300 PSI (21 bar).
FWD MAX, REV MAX setting
incorrect
Reset drive speeds using EZ-Cal
Wheel motor not functioning
correctly
Inspect wheel motors for damage or wear.
Poor grade-ability or drive
performance
Wheel motor not functioning
correctly
Inspect wheel motors for excessive bypass or shift not working properly
Hydraulic oil incorrect for severe
low temperatures
Use hydraulic tank warmer if equipped. Operate drive continuously until
drive begins to operate.
Planetary hub bypass engaged
Check bypass plates located in the center of each planetary hub. Should
be convex. Turn over if not.
Low pump charge pressure
Check at Brake/Axle manifold, should be 300 PSI (21 bar).
Adjust charge pressure to 300 PSI (21 bar).
Incorrectly adjusted or worn
hydraulic drive pump
See Hydraulics Section for pump adjustment. Inspect or replace pump.
Drive in one direction only
Drive valve not energizing in one
direction
Check 12 volts to coil. Check coil. Check valve function (located on top of
drive pump).
No output from GP500 Module
Check output from GP500 2Fl, P4-2 (FWD) and P4-3 (REV)
Drive joystick output failure
Check drive joystick output from GP500 (see 2E2, P10-1)
