Electronic DISTRIBUTORLESS Ignition System (EDIS)

System is used on 6-cylinder engines and consists of a Variable Reluctance Sensor (VRS), an EDIS ignition module, an ECA and one 6-tower coil pack.

During system operation, EDIS ignition module receives crankshaft position information from VRS. In turn, EDIS ignition module generates a Profile Ignition Pickup (PIP) signal and sends it to ECA. The ECA responds with a Spark Angle Word (SAW) signal containing advance or retard timing information which it sends back to EDIS module. The EDIS ignition module then processes VRS and SAW signals and decides which coils to fire. In addition, EDIS ignition module generates an ignition Diagnostic Monitor (DM) signal and sends it to ECA which uses it during failure mode to provide a tach output signal.

The VRS, which transmits crankshaft position, is a passive electromagnetic device senses movement of a 35-tooth wheel with a gap where the 36th tooth would be, located behind crankshaft pulley (missing tooth is at 60° BTDC). An AC voltage signal, generated by VRS, increases with engine RPM and provides basic spark timing information to EDIS ignition module.

The EDIS ignition module is a microprocessor that makes decisions about spark timing and coil firing. The EDIS ignition module turns coils on and off at correct time and in proper sequence, based on information from VRS and SAW signal generated from ECA. The EDIS ignition module, upon receiving VRS and SAW signals, produces PIP and IDM output signals which are sent to ECA.

The ECA receives IGN GND and PIP signals from EDIS ignition module then generates a SAW output signal, based upon fuel, air and other sensor information. An IDM signal is received from EDIS ignition module to determine if a failure mode should be recorded.

The coil pack receives active low signals from EDIS ignition module and fires 2 spark plugs at once. One plug is for cylinder which is to be fired (On compression stroke) and other goes to mating cylinder which is on exhaust stroke. The next time coil is fired situation is reversed. The next pair of spark plugs is fired according to engine firing order.