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Discussion Starter #1
How to test a coil on plug type coil
Each coil is held in place by a single bolt; take out that little bolt. Disconnect the electrical connector to the coil, and then the coil and wire. You can test the coil with a digital ohmmeter.

There are two wires inside the connector and then a larger one that goes to the plug.
test across the two small connectors for the primary windings, and then from the little one that is marked bat or B+ to the large wire that goes to the plug for the secondary windings.

Using a digital voltmeter.
The primary circuit from B+ to tach should be 0.3 - 1.0 ohms
The secondary windings (B+ to plug wire) should measure about 5.9K ohms (that is the measurement I got off of two new ones), I do not know what the acceptable range is.
 

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Clarification Request

Using a digital voltmeter.
The primary circuit from B+ to tach should be 0.3 - 1.0 ohms
The secondary windings (B+ to plug wire) should measure about 5.9K ohms (that is the measurement I got off of two new ones), I do not know what the acceptable range is.
Am I correct in assuming the "plug wire" noted in the above procedure on the Ford 3.0L COP is the spring? In my tests, the 2 small connectors on the COP tested to around .9 - 1.0 ohms on all. However, I can't get any reading from either small pin and the spring. Could you clarify how the secondary winding test is done? Sure I am doing it wrong!

Many thanks!:thumbsup:
 

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Yes, Try removing the boot and spring from the coil and test again, they just pull off. If you still have no reading from B+ to plug wire the coil is shot....open windings.

BTW: The resistance from the plug wire connector to B+ should be around 6,000 to 8,000 ohms as already indicated above (5.9K ohms). Readings higher than 10K ohms can damage the coil driver circuit in the PCM. I use dielectric grease on the plug wire connections.
 

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Discussion Starter #4
Cuda_Jim, thanks for adding that additional information! :)
 

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If you have any corrections, additions, or pictures that you would like to add to this HowTo, please PM me, and I'll open it to give you access to it.
Thanks
 
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