140-3 SERIES
12-203
TROUBLESHOOTING POINTS TO REMEMBER WHEN TROUBLESHOOTING
POINTS TO REMEMBER WHEN TROUBLESHOOTING
Stop the machine in a level place, and check that the safety pins and blocks are securely fitted, and the
parking brake is securely applied.
When carrying out the operation with two or more workers, keep strictly to the agreed signals, and do not
allow any unauthorized person to come near.
If the radiator cap is removed when the engine is still hot, boiling water may spurt out and cause serious
burns. Always wait for the water temperature to go down before removing the radiator cap.
Be extremely careful not to touch any hot parts or to get caught in any rotating parts.
When disconnecting wiring, always disconnect the negative (–) terminal of the battery first.
When removing a plug or cap from a location which is under pressure from oil, water, or air, always release
the internal pressure first. When installing measuring equipment, be sure to connect it properly.
The aim of troubleshooting is to pinpoint the basic cause of the failure, to carry out repairs swiftly, and to prevent
reoccurrence of the failure. When carrying out troubleshooting, and important point is of course to understand
the structure and function. However, a short cut to effective troubleshooting is to ask the operator various
questions to form some idea of possible causes of the failure that would produce the reported symptoms.
1. When carrying out troubleshooting, do not
hurry to disassemble the components
If components are disassembled immediately
any failure occurs:
• Parts that have no connection with the failure
or other unnecessary parts will be
disassembled
• It will become impossible to find the cause of
the failure.
It will also cause a waste of man-hours, parts, or
oil or grease, and at the same time, will also lose
the confidence of the user or operator.
For this reason, when carrying out
troubleshooting, it is necessary to carry out
thorough prior investigation and to carry out
troubleshooting in accordance with the fixed
procedure.
2. Points to ask user or operator
1) Have any other problems occurred apart
from the problem that has been reported?
2) Was there anything strange about the
machine before the failure occurred?
3) Did the failure occur suddenly, or were there
problems with the machine condition before
this?
4) Under what conditions did the failure occur?
5) Had any repairs been carried out before the
failure? When were these repairs carried
out?
6) Has the same kind of failure occurred
before?
3. Checks before troubleshooting
1) Is there any sign of abnormality in the
machine or engine?
2) Always carry out the Checks before starting.
3) Carry out other checks if necessary.
4) Other maintenance items can be checked
externally, so check any item that is
considered to be necessary.
5) Check for any error display on the controller.
4. Confirming failure
Confirm the extent of the failure yourself, and
judge whether to handle it as a real failure or as
a problem with the method of operation, etc.
★ When operating the machine to re-enact the
troubleshooting symptoms, do not carry out
any investigation or measurement that may
make the problem worse.
5. Troubleshooting
Use the results of the investigation and
inspection in Items 2 – 4 to narrow down the
causes of failure, then use the troubleshooting
matrix or flowchart to locate the position of the
failure exactly.
★ The basic procedure for troubleshooting is
as follows.
1) Start from the simple points.
2) Start from the most likely points.
3) Investigate other related parts or
information.
6. Measures to remove root cause of failure
Even if the failure is repaired, if the root cause of
the failure is not repaired, the same failure will
occur again.
To prevent this, always investigate why the
problem occurred. Then, remove the root cause.
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