Isuzu 2008MY N Series, Руководство по ремонту

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1A-344 Engine Control System (4HK1)
Intermittent Conditions
Checks Action
Definition:
The problem is not currently present but is indicated in DTC History.
OR
There is a customer complaint, but the symptom cannot currently be duplicated, if the problem is not DTC related.
Preliminary Checks • Refer to Symptoms - Engine Controls before starting.
Harness/ Connector Many intermittent open or shorted circuits are affected by harness/ connector
movement that is caused by vibration, engine torque, bumps/ rough pavement,
etc. Test for this type of condition by performing the applicable procedure from
the following list:
• Move related connectors and wiring while monitoring the appropriate scan
tool data.
• Move related connectors and wiring with the component commanded ON,
and OFF, with the scan tool. Observe the component operation.
• With the engine running, move related connectors and wiring while
monitoring engine operation.
If harness or connector movement affects the data displayed, component/
system operation, or engine operation, inspect and repair the harness/
connections as necessary.
Electrical Connections or Wiring Poor electrical connections, terminal tension or wiring problems cause most
intermittent. To perform the following inspections:
• Poor mating of the connector halves, or terminals improperly seated in the
connector body.
• Improperly formed or damaged terminals. Test for poor terminal tension.
• Poor terminal to wire connections including terminals crimped over
insulation. This requires removing the terminal from the connector body.
• Corrosion/ water intrusion. Pierced or damaged insulation can allow
moisture to enter the wiring. The conductor can corrode inside the
insulation, with little visible evidence. Look for swollen and stiff sections of
wire in the suspect circuits.
• Wires that are broken inside the insulation.
• Harness for pinched, cut or rubbed through wiring.
• Ensure that the wiring does not come in contact with hot exhaust
components.
Control Module Power and
Grounds Component Power and
Grounds Poor power or ground connections can cause widely varying symptoms.
• Test all control module power supply circuits. Many vehicles have multiple
circuits supplying power to the control module. Other components in the
system may have separate power supply circuits that may also need to be
tested. Inspect connections at the module/ component connectors, fuses,
and any intermediate connections between the power source and the
module/ component. A test lamp or a DMM may indicate that voltage is
present, but neither tests the ability of the circuit to carry sufficient current.
Ensure that the circuit can carry the current necessary to operate the
component.
• Test all control module ground and system ground circuits. The control
module may have multiple ground circuits. Other components in the system
may have separate grounds that may also need to be tested. Inspect
grounds for clean and tight connections at the grounding point. Inspect the
connections at the component and in splice packs, where applicable.
Ensure that the circuit can carry the current necessary to operate the
component.
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