The electronic ignition (EI) system is responsible for producing and controlling a high energy secondary spark. This spark is used to ignite the compressed air/fuel mixture at precisely the correct time. This provides optimal performance, fuel economy, and control of exhaust emissions. This ignition system consists of a separate ignition coil connected directly to each spark plug, known as coil on plug. These coil assemblies are located in the center of the camshaft cover. The driver modules within each coil assembly are commanded ON/OFF by the powertrain control module (PCM). The PCM primarily uses engine speed and position information from the crankshaft and camshaft position sensors to control the sequence, dwell, and timing of the spark. The EI system consists of the following components:

The crankshaft position (CKP) sensor is a permanent magnet generator, known as a variable reluctance sensor. The magnetic field of the sensor is altered by a crankshaft mounted reluctor wheel that has seven machined slots, 6 of which are equally spaced 60 degrees apart. The seventh slot is spaced 10 degrees after one of the 60 degree slots. The CKP sensor produces seven pulses for each revolution of the crankshaft. The pulse from the 10 degree slot is known as the sync pulse. The sync pulse is used to synchronize the coil firing sequence with the crankshaft position. The CKP sensor is connected to the powertrain control module (PCM) by a signal circuit and a low reference circuit.

The camshaft position (CMP) sensor is triggered by a notched reluctor wheel built into the exhaust camshaft sprocket. The CMP sensor provides 6 signal pulses every camshaft revolution. Each notch, or feature of the reluctor wheel is of a different size for individual cylinder identification. This means the CMP and crankshaft position (CKP) signals are pulse width encoded to enable the powertrain control module (PCM) to constantly monitor their relationship. This relationship is used to determine camshaft actuator position and control its phasing at the correct value. The PCM also uses this signal to identify the compression stroke of each cylinder, and for sequential fuel injection. The CMP sensor is connected to the PCM by a 12-volt, low reference, and signal circuit.

Each ignition coil has an ignition 1 feed and a ground. The PCM supplies an ignition control (IC) circuit. Each ignition coil contains a solid state driver module as its primary element. The powertrain control module (PCM) signals the coil driver to initiate a firing event by applying a signal to the IC circuit at the appropriate time. When the signal is removed, the coil fires the spark plug. The spark plugs are tipped with platinum for long wear and higher efficiency.

The powertrain control module (PCM) controls all ignition system functions, and constantly corrects the spark timing. The PCM monitors information from various sensor inputs that include the following:

During normal operation the powertrain control module (PCM) controls all ignition functions. If either the crankshaft position (CKP) or camshaft position (CMP) sensor signal is lost, the engine will continue to run because the PCM will default to a limp home mode using the remaining sensor input. As mentioned above, each coil is internally protected against damage from excessive voltage. If one or more coils were to fail in this manner, a misfiring condition would result. Diagnostic trouble codes are available to accurately diagnose the ignition system with a scan tool.