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4. Troubleshooting
4.1 General Information
4.1.1 Before replacing controllers
Do not replace controllers casually even if replacement
is required as a result of troubleshooting. Be sure to
check the following items before replacing controllers.
• Loose battery connectors
• Abnormal wire harness connections
• Loose connectors
• Broken, bent or loose connector pins
• Dirty connectors
If connectors are dirty, remove the connector and
clean connectors. See “How to clean harness con-
nectors and system components” on the next page.
• Ensure that the main harness is not short-circuited
to the truck body.
If any of these items (above items) is a source of the
trouble, the controller will be damaged even if it is re-
placed with a new one. Be sure to check the above
items and replace carefully.
4.1.2 Connection of service tool
(1) Turn off the truck power.
(2) Find the service tool connector in the CAB har-
ness.
(3) Remove the cover and connect the PC as shown.
(4) Turn on the truck power.
(5) Start the service tool software.
4.1.3 Diagnostic Precautions
(1) Before measuring voltage, check the battery for
charged condition and specific gravity. If system
inspection is performed with the battery uncharged
or reduced in specific gravity, accurate measure-
ments cannot be achieved.
(2) To avoid having electrical parts damaged, set the
starter switch to OFF before disconnecting and re-
connecting battery cables.
(3) Before disconnecting connectors, set the starter
switch to OFF then allow at least 20 seconds. Volt-
age may remain in electric parts or connected cir-
cuit.
(4) When performing measurement with the tester,
handle the test bar carefully so that it does not
damage internal circuit and other electrical parts of
the electronic control unit to result in a short-circuit
failure between terminals in connector or between
connector and truck body.
(5) Resistance is affected by temperature. Determine
the necessity of resistance measurement following
given temperature specification as a guide. Other-
wise, use normal temperature (10 to 35°C) as the
measuring condition.
GSE cable
VCM-3
GSE
VCM-3OP
GSE
CAB harness
212346
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