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Old 10-13-2008, 10:54 AM   #6
Stephen Max
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Hmmm. Usually when testing resistance with a multimeter it shows 0 when there is continuity in a closed circuit with no resistance. Infinite resistance is indicated by something else, like a dash or some other non-numerical display.

Another problem with testing resistance to determine failure of a coil is that ignition coil failure is almost always an insulation breakdown when the coil is hot, so you should test with a coil that is up to temperature. Even then it may not indicate anything is wrong, since insulation usually fails when there is (significant) voltage present, and a multimeter is not going to give enough voltage to cause an insulation failure. So you may end up with a false negative (i.e. no indication of anything wrong) with this method.

A high-pot test would be conclusive, but that takes special equipment that the home mechanic doesn't usually have.
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