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- How to Diagnose31
Normal close (NC) type
Deenergized stateEnergized state
Current does not flow
Z1680235
State of fuse blown due to overcurrent
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I21680237
State of fuse blown due to thermal fatigue
Z1660236When a normal close type relay as illustrated here is
checked, there should be continuity between terminals
(1) and (2) and between terminals 3 and 4 when the relay
is deenergized, and the continuity should be lost betweenterminals 3 and 4 when the battery voltage is applied
to the terminals
1 and 2. A relay can be checked in this
manner and it cannot be determined if a relay is okay
or faulty by checking its state only when it is deenergized
(or energized),
CHECKING FUSESA blade type fuse has test taps provided to allow checking
of the fuse itself without removing it from the fuse block. Thefuse is okay if the test light comes on when its one lead is
connected to the test taps (one at a time) and the other lead
is grounded. (Change the ignition switch position adequatelyso that the fuse circuit becomes live.)
CAUTIONS IN EVENT OF BLOWN FUSE
When a fuse is blown, there are two probable causes as follows:One is that it is blown due to flow of current exceeding its
rating.The other is that it is blown due to repeated on/off current
flowing through it. Which of the two causes is responsible
can be easily determined by visual check as described below.(1) Fuse blown due to current exceeding rating
The illustration shows the state of a fuse blown due to
this cause. In this case, do not replace the fuse with a
new one hastily since a current heavy enough to blow
the fuse has flowed through it. First, check the circuit
for shorting and check for abnormal electric parts. Only
after the correction of such shorting or parts, fuse of the
same capacity should be used as a replacement. Never
use a fuse of larger capacity than the one that has blown.
If such a fuse is used, electric parts or wirings could be
damaged before the fuse blows in the event an overcurrent
occurs again.(2) Fuse blown due to repeated current on/off
The illustration shows the state of a fuse blown due to
repeated current on/off. Normally, this type of problem
occurs after fairly long period of use and hence is less
frequent than the above type. In this case, you may simplyreplace with a new fuse of the same capacity.
1 TSB Revision
