Below is video tutorial about automotive ignition coil. The coil is composed of primary and secondary circuit. The primary circuit is consist of two terminals. It’s connected to the steady 12 volts battery and ignition module or ECM. The secondary circuit is connected to the spark and carry a high voltage.
The ECM module will always looks for returning voltages through the coil it self. To test, simply put a probe with a multimeter to the ECM. IF there’s no voltages, engine off. For further information about the automotive ignition coil, watch the entire video.