Ignition System: Description and Operation

System Diagram:

The Electronic Distributorless Ignition System (EDIS) consists of the following components:

1. Variable reluctance crankshaft timing sensor (VRS).
2. EDIS ignition module.
3. Ignition coil pack consisting of three separate coils.
4. EEC processor within the ECA computer.
5. Spark plugs.
6. Spark plug wires and other related wiring.

The EDIS operates by sending crankshaft position information from the VRS sensor to the EDIS module. The module generates a PIP (Profile Ignition Pickup) output signal and sends it to the EEC processor (also referred to as the Electronic Control Assembly or ECA). The processor responds back to the EDIS module with a SAW (Spark Angle Word) signal containing advance or retard timing information. The module processes the VRS and SAW signals and decides which coils to fire. The module also generates an IDM (Ignition Diagnostic Monitor) signal to the processor which is used to indicate a failure mode and provide a tach output signal.