The EDIS system consists of a Variable Reluctance Sensor (VRS), an Ignition Control Module (ICM), a PCM and two 4-tower coil packs (4-cylinder) or one 6-tower coil pack (V6).
During system operation, ICM receives crankshaft position information from CKP sensor. In turn, ICM generates a Profile Ignition Pick-Up (PIP) signal and sends signal to PCM. The PCM responds with a SPOUT signal containing advance or retard timing information, which is sent to ICM. The ICM then processes CKP and SPOUT signals and determines which coils to fire. In addition, ICM generates an Ignition Diagnostic Monitor (IDM) signal and sends signal to PCM, which uses it during failure mode to provide a tach output signal.
The CKP sensor is an electromagnetic device that senses movement of a 35 tooth wheel, located behind the crankshaft pulley. Each tooth is positioned in 10 degree increments with an empty slot (missing tooth) located BTDC. The detection of the missing tooth is what enables the PCM to identify crankshaft position and initiate correct firing order.
The ICM is a microprocessor with coil drivers. ICM strategy controls spark timing and coil firing. The ICM turns coils on and off at the correct time and in proper sequence, based on information from CKP sensor and a pulse width modulated signal (SPOUT) generated from ICM. The coil is turned on (coil charging) by ICM, and then turned off, firing 2 spark plugs at once. One plug is fired on the compression stroke; the other plug fires the mating cylinder, which is on the exhaust stroke. On the next cycle, firing strategy is reversed.