JLG sky trak mmv Service Manual page 348

Hydraulic System
Before troubleshooting any
hydraulic circuit, ALWAYS
begin by checking the
following:
1. Hydraulic oil level in the
reservoir
2. All hoses, tubes, fittings
for leaks, kinks,
interference, etc.
3. Air in the lines
NOTE:
When checking pressures in
circuits, refer to Section 9.7,
Hydraulic System Testing for
correct pressure readings.
9.50
If the joystick is not
functioning, check the
electrical components
of the circuit.
Check the pilot pressure at
"PPG" port of secondary
function manifold.
If OK
Inspect collar for looseness
on joystick assembly.
If OK
Replace joystick valve.
Refer to Section 10.13.10,
Not
OK
Joystick .
If OK
Adjust/install new seal kit/
replace the pressure reducing
Not
OK cartridge on the secondary
function manifold.
If loose, replace
Not
joystick valve.
OK
Model MMV Rev. 12/04