Testing COP systems can be challenging. There is a reason our big box ignition analyzers are sitting in the corner of the shop collecting dust. COP systems make secondary ignition voltage difficult to obtain. Matt Shananhan explains what did with a 2008 Toyota Corolla with a misfire and check engine light with P0354: Ignition coil “D” primary/secondary circuit.

The question is, why was the vehicle misfiring if the coil was still firing OK?

The blue is from the #1 COP, captured with a synch probe.
The red is the feedback circuit.
The green is the ignition coil current.

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