MAC TOOLS EM721 Manual Del Usuario página 50

Connect:
•
Black test probe to the negative (cathode) side of the diode pack.
•
Red test probe to the positive (anode) side of the diode pack.
If neither diode is shorted, about 0.8V should be displayed.
If one diode is shorted, about 0.4V should be displayed.
If wire is open, both diodes are open, or the voltage drop is above 2V, OFL (OverFLow) should be displayed.
IGNITION SYSTEM TESTS
If you suspect a bad ignition wire, test resistance of the wire while moving, twisting, or bending the wire. The
resistance values will typically be around 10kΩ per foot.
If you suspect a problem with the ignition coil, check the resistance of the ignition coil's primary and secondary
windings. This test needs to be done both when the coil is hot and when it is cold. You should also measure
from the coil's case to each connector and between the primary and secondary windings to insure they are not
shorted together. The primary windings should have a very low resistance – typically from a few tenths of an
ohm to a few ohms. The secondary windings should have a much higher resistance – typically in the 10kΩ
range. To get the actual figures for a specific coil, check the manufacturer's specifications.
Spark Plug Wire (Secondary Ignition Wire) Resistance Test
TO AVOID ELECTRICAL SHOCK, ALWAYS DISCONNECT THE IGNITION COIL FROM
If spark plugs are more than two years old or if there are other indications of ignition system problems, check
the spark plug wires.
NOTE:
Be careful when pulling the spark plug boot from the insulator as bonding may have occurred.
This test checks for high resistance or open circuits in the secondary ignition wires (spark plug wires).
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WARNING
THE IGNITION SYSTEM BEFORE TESTING.
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