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Re: COP with 3 wires..what is the 3rd wire doing and why?
Posted to Technical Theory Forum on 3/8/2002

Hi Craig,

I'm not sure I understand the question but the coil needs one wire for power, one for ground (so the ICM can ground the primary) and one for the ignition control signal from the PCM to trigger the ICM. There is no way to look at primary voltage her... Login to read more.