What does the primary circuit on the coil do?
What does the primary circuit on the coil do? The Primary circuit includes battery voltage (B+) terminal attached to a 12-volt current source and a ground (B-) terminal attached to a power transistor that controls primary current flow. To create a spark, the transistor is commanded by the PCM to form a magnetic field by grounding the primary coil. Can a bad coil ruin a spark plug? Yes. Bad ignition coils can damage and or cause spark plugs to degrade prematurely. Since a faulty ignition coil causes a misfire, it will also cause the related spark plugs to foul. Always...