Troubleshooting; Transmission Troubleshooting - JLG sky trak mmv Service Manual

7.9

TROUBLESHOOTING

This section provides an easy reference guide covering
the most common problems that may occur during oper-
ation of the transmission.
Note: Contact the JLG Service Department at
1-717-485-5161 (Domestic) or 1-877-554-5438 (Interna-
tional) if internal transmission repair is required during
the warranty period.
7.9.1

Transmission Troubleshooting

Problem
1. Transmission will not engage,
or will not shift properly.
2. Low or no pump flow or
pressure.
Model MMV Rev. 12/04
Detailed transmission service instructions (covering repair,
disassembly, reassembly and adjustment information) are
provided in the ZF 4 WG-98 Transmission Repair Manual,
(ZF part number 5871 139 002, JLG part number
8990418).
The transmission should be checked, serviced and re-
paired only by experienced service technicians who are
aware of all safety instructions and particular component
features.
Cause
1. Oil level too high or low.
2. Travel select lever not
functioning properly and/or a
fault in the wiring harness.
2. Transmission valve body
solenoids not functioning
properly.
3. Pilot-operated shift valves not
operating properly.
3. Pump output pressure low.
4. Clutch piston o-rings damaged.
5. Clutch discs worn or damaged.
6. Coupling shafts or gear teeth
damaged.
1. Low oil level.
2. Transmission filled with incorrect
oil, or oil contaminated.
3. Pump suction pipe screen
clogged.
4. Central shaft damaged.
5. Pump worn or damaged.
Transmission: ZF 4 WG-98 TS
Remedy
1. Fill transmission to correct level
with recommended oil (refer to
Section 2.13.10, a.
Transmission Oil Level Check ).
2. Refer to Section 10.13.8, b.
Travel Select Lever and Wiring
Harness Testing .
2. Refer to Section 10.13.8, c.
Upper and Lower Transmission
Valve Body Solenoid Testing .
3. Clean the valve spool and
housing. Replace return spring
as needed.
4. Refer to Section 7.9.1,
Transmission Troubleshooting,
Step 2, Low or no pump flow or
pressure.
5. Replace o-rings.
6. Replace clutch discs.
7. Replace couplings.
1. Fill transmission to correct level
with recommended oil (refer to
Section 2.13.10, a.
Transmission Oil Level Check ).
2. Drain transmission and fill to
correct level with recommended
oil (refer to Section 2.13.10, b.
Transmission Oil and Filter
Change ).
3. Clean, repair and/or replace
suction pipe.
4. Replace central shaft.
5. Repair or replace pump
assembly.
7.19