Transmission
6-7
6036, 6042, 8042, 10042, 10054 31211015
6.5 TRANSMISSION TROUBLESHOOTING
This section provides an easy reference guide covering the
most common problems that may occur during operation of
the transmission.
Note: Contact the JLG Service Department if internal
transmission repair is required during the warranty period.
The transmission should be checked, serviced and repaired
only by experienced service technicians who are aware of all
safety instructions and particular component features.
Problem Cause Remedy
1. Transmission will not engage or
will not shift properly.
1. Oil level too high or low. 1. Fill transmission to correct level.
Refer to Section 2.3, “Fluid
Specifications”.
2. Transmission control lever not
functioning properly and/or a
fault in the wiring harness.
Transmission control lever not
functioning properly and/or a
fault in the wiring harness.
2. Refer to Section 9.5, “Electrical
System Schematics”.
3. Transmission valve body
solenoids not functioning
properly.
3. Refer to Section 9.5, “Electrical
System Schematics”.
4. Pilot-operated shift valves not
operating properly.
4. Clean the valve spool and
housing. Replace return spring as
needed.
5. Pump output pressure low. 5. Refer to Section 6.5, “Transmission
Troubleshooting”, Problem 2 “.
6. Clutch piston o-rings damaged. 6. Replace o-rings.
7. Clutch discs worn or damaged. 7. Replace clutch discs.
8. Coupling shafts or gear teeth
damaged.
8. Replace couplings.
2. Low or no pump flow or
pressure.
1. Low oil level. 1. Fill transmission to correct level.
Refer to Section 2.3, “Fluid
Specifications”.
2. Transmission filled with incorrect
oil, or oil contaminated.
2. Drain transmission and fill to
correct level. Refer Section 2.3,
“Fluid Specifications”.
3. Pump suction pipe screen
clogged.
3. Clean, repair and/or replace
suction pipe.
4. Central shaft damaged. 4. Replace central shaft.
5. Pump worn or damaged. 5. Repair or replace pump assembly.
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