The ignition coil current flow is provided by the Powertrain Control Module (PCM) through a switched ground signal, which comes from the coil driver. Once the coil driver is turned on, the current is immediately stored until it reaches a maximum value, which is determined by the inductance and resistance of the coil. After the current is turned off, a secondary high voltage surge is created in the magnetic field, which is why the spark plug is triggered.
This high voltage surge creates a return voltage to the PCM, which uses it to perform ignition diagnostics. The ignition system is constantly monitored by the PCM for proper ignition performance. When a voltage short is detected in the secondary circuit of the ignition coil “A”, the DTC P2302 OBDII code is set.