California

DESCRIPTION AND OPERATION

Electronic Distributorless Ignition System (EDIS) Module:

The Ignition Control Module (ICM) used in this electronic ignition system is a microprocessor-based device with coil drivers and operates in the following manner:
1. Receives crankshaft position and speed information from the Crankshaft Position (CKP) sensor, and desired spark advance (SPOUT) information from the Powertrain Control Module (PCM).
2. Uses the information from the crankshaft position sensor and powertrain control module to direct which ignition coil to fire, and controls the turn ON/OFF times of the ignition coil to achieve the correct dwell and spark advance.
3. Synthesizes a Profile Ignition Pickup (PIP) signal and an Ignition Diagnostic Monitor (IDM) signal for use by the powertrain control module control strategy.
4. Sends information on system failures through the IDM signal to the powertrain control module which stores information for use during the diagnostic test mode. The Ignition Diagnostic Monitor (IDM) signal also drives the tachometer.

Failure Mode Effects Management
During some Electronic Ignition (EI) system faults, the Failure Mode Effects Management (FMEM) portion of the Ignition Control Module (ICM) will maintain vehicle operation. If the ignition control module does not receive the SPOUT input, it will automatically turn the ignition coils ON and OFF using the CKP signal. However, this condition will result in fixed spark timing (10 degrees BTDC).

Ignition Diagnostic Monitor
The Ignition Diagnostic Monitor (IDM) is a function of the Ignition Control Module (ICM). The ignition control module sends information on system failures to the PCM, which stores the information for use in diagnostic test mode. The IDM signal is also used to drive the vehicle instrument tachometer.