Sakai SV400D-2, Руководство по ремонту

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9-003
ELECTRICAL SYSTEM TROUBLESHOOTING
2. ELECTRICAL SYSTEM TROUBLESHOOTING
2-1. When Performing Electrical System Fault Diagnosis
WARNING
When a failure occurs due to a faulty contact or other such cause, use caution because the
equipment can return to normal during an inspection and suddenly operate properly.
2-1-1. Precautions to take during electric circuit fault diagnosis
When disconnecting or connecting a connector, be sure to turn the power supply OFF.
Since connectors are not numbered, be sure to affix alignment marks so that you can restore
them to their original condition.
Before making a diagnosis, check related connectors for faulty connections.
(Check by disconnecting and reconnecting related connectors several times.)
Before proceeding to the next step, be sure to return the disconnected connectors to their
original condition.
When diagnosing a circuit (measuring the voltage, resistance, continuity and current), move
related wiring and connectors several times, and check whether the tester’s numerical values
change. (If values change, faulty contact in the circuit is possible.)
2-1-2. Inspection of electrical system
Operate the applicable switches and turn the relays ON and OFF. Ultimately, if the solenoid valve
operates (makes a sound) and the pump runs, the electrical system is OK.
If there is a failure (fault), narrow the range of the inspection to the six broad steps described
below.
1) Grounding inspection
Check for disconnected or loose grounding. If rust is present (which can cause faulty contact),
remove the rust.
2) Fuse inspection
2-1) Check for fuse disconnections and corrosion.
2-2) If fuse is burned out
Check whether a pump or valve (that is supposed to be protected by a burnt fuse) burned,
and whether there is a burning odor.
If a pump or valve is not burned particularly, check the harness for signs of burning. If it is
burned, replace it.
If a fuse is burnt and a relay along the pathway has failed, replace it. And if there is a timer,
replace the timer, too. If a switch visually appears to be unsatisfactory (burned, melted, etc.)
even though it operates, replace it.
Simply replacing a fuse may not eliminate the true cause of a problem, and over current may
flow again. Also, if over current secondarily causes an electrical path to fail (such as a wiring
meltdown inside a solenoid valve), current will not flow. Thus, a fuse may not burn out, but it
also will not operate. If you do not know the location of burning or of an odor, investigate as
described follows.
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