Circuit Operation

With the starter switch in ON or START battery voltage is applied to the Powertrain Control Module (PCM), various engine sensors, and the ignition coils. When the engine is cranked to start, the crank shaft position (CKP) sensor sends timing information directly to the PCM, which breaks the ground path in the primary of the ignition coils, thus creating a high voltage secondary impulse which fires the spark plugs, and the engine starts. The PCM receives information such as tiring order and starting timing at each ignition coil from the CKP sensor. The PCM relies on information from various engine sensors to determine correct ignition timing.