Lull 944E-42, Service Manual

Page: 189 / 844

6.15 Model 644E-42/944E-42 Rev. 6/04
Transmission: ZF 4WG-92/98 TSC & Transfer Case: ZF TB92-I4
6.8 TROUBLESHOOTING
This section provides an easy reference guide covering
the most common problems that occur during operation
of the transfer case.
Note: Contact your local Lull distributor or the JLG
Service Department at (877) 554-5438 or
(717) 485-6657, if internal transfer case repair is
required during the warranty period.
Detailed transmission service instructions covering repair,
disassembly, reassembly, adjustment and troubleshooting
information is provided in the ZF Model 4WG 92/98 TSC
Transmission Operating and Repair Manual, JLG P/N
8990495
(ZF part number 5871.134.002).
The transmission should be checked, serviced and
repaired only by experienced service technicians who are
aware of all safety instructions and particular component
features.
6.8.1 Transmission Troubleshooting
Problem Cause Remedy
1. Transmission will not engage,
or will not shift properly.
1. Oil level too high or low.
2. Travel select lever not
functioning properly and/or a
fault in the wiring harness.
3. Transmission valve body
solenoids not functioning
properly.
4. Pilot-operated shift valves not
operating properly.
5. Pump output pressure low.
6. Clutch piston o-rings damaged.
7. Clutch discs worn or damaged.
8. Coupling shafts or gear teeth
damaged.
1. Fill transmission to correct level
with Universal Tractor Fluid.
(Refer to the appropriate
Owners/Operators Manual.)
2. Refer to Section 9.14.8,
“Transmission Shift Control
Switch.”
3. Refer to Section 9.14.9,
“Transmission Solenoid Valves.”
4. Clean the valve spool and
housing. Replace return spring
as needed.
5. Refer to Section 6.8.1,
“Transmission Troubleshooting,”
Problem 2. “Low or no pump
flow or pressure.”
6. Replace o-rings.
7. Replace clutch discs.
8. Replace couplings.
2. Low or no pump flow or
pressure.
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.
1. Fill transmission to correct level
with Universal Tractor Fluid.
(Refer to the appropriate
Owners/Operators Manual.)
2. Drain transmission and fill to
correct level with Universal
Tractor Fluid. (Refer to the
appropriate Owners/Operators
Manual.)
3. Clean, repair and/or replace
suction pipe.
4. Replace central shaft.
5. Repair or replace pump
assembly.