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ignition coil polarity

PostPosted: August 3rd, 2010, 7:20 am
by grumpyvette
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Checking Ignition Coil Polarity

You can test for correct polarity of the ignition coil by using a voltmeter. Connect the negative lead to the (-) negative terminal and the positive lead to the engine block.

Set the meter on the highest volt range (these connections are the same whether you have a positive ground or negative ground electrical system). The secondary winding's polarity, which you are testing, is determined by the combined hookup of the battery and primary windings.

Crank the engine over (do not start it) and the needle of the voltmeter should show an

upward swing to the plus or positive side (do not worry about taking a reading). If volt meter the needle swings down to the negative side and gives a negative reading, your coil is hooked up backwards. To correct the polarity, simply reverse coil primary leads.

A coil with reversed polarity will have about a twenty percent lower output which may not show up at idle and low rpms, but can cause an engine to miss or stumble under load and at higher engine rpms.

Connect the red test lead of a digital ohmmeter to the primary side of the coil and the black test lead of the ohmmeter to the secondary side of the coil. The displayed reading on the ohmmeter should be between 0.7 and 1.7 ohms. You may have a faulty ignition coil if the readings displayed on your ohmmeter are not within this range.

Connect the red test lead of the ohmmeter to the coil's high-tension terminal and connect the black test lead to the coil's negative connection. The reading displayed on the ohmmeter should fall between 7,500 and 10,500 ohms. Your coil may be failing if the reading is not within this range.

Read more: How to Diagnose a Faulty Ignition Coil | ... z21gN3XOmC