Hyundai HL955 Manual page 141

Problem
Transmission shifts too
fast
Machine "creeps"
in neutral
Transmission hydraulic
system overheats
Cause
Wrong transmission controller.
System pressure too high.
Stuck PPC valve.
Stuck or missing check valves.
Missing O-r ing from end of
modulation orifice.
Broken piston return spring.
Incorrect transmission oil.
War ped disks and plates in
transmission.
High oil level.
Low oil level.
Wrong oil grade.
Park brake dragging.
Pinched, restricted or leaking lube
lines.
Machine operated in too high
gear range.
Malfunction in temperature gauge
or sensor.
Restricted air flow through oil
cooler or radiator.
Failed oil cooler bypass valve (In
thermal bypass valve).
Failed thermal bypass valve.
Internally restricted oil cooler.
Leakage in transmission hydraulic
system.
Malfunction in converter relief
valve.
Low transmission pump output.
3-85
Remedy
Check if transmission controller has been
changed
Do transmission system pressure test.
Remove and inspect PPC valve.
Replace if necessary. Also remove end cover
to inspect PPC valve and control valve housing.
Replace if necessary.
Inspect transmission control valve.
Remove orifice and inspect port for O-ring.
Disassemble and inspect clutch.
Change oil (SAE 10W-30/15W-40).
Check transmission.
Transmission overfilled or hydraulic pump seal
leaking.
Add oil.
Change oil.
Check for heat in park brake area.
Check cooler lines.
Operate machine in correct gear range.
I n s t a l l t e m p e ra t u r e s e n s o r t h e ve r i f y
temperature.
Do tachometer/temperature reader installation
procedure.
Do radiator air flow test.
Disassemble and inspect.
Remove thermal bypass valve and check to see
if machine still overheats. Do transmission oil
cooler thermal bypass valve test.
Do oil cooler restriction test.
Do transmission system pressure, element
leakage test.
Do converter out pressure test.
Do transmission pump flow test.