Ignition Control Module: Description and Operation
DESCRIPTION AND OPERATIONElectronic Distributorless Ignition System (EDIS) Module:
Ignition Control Module (ICM)
Ignition Control Module Pinout:
Ignition Control Module Pinout
Ignition System Diagram:
Ignition System Diagram
The Ignition Control Module (ICM) receives the Crankshaft Position Sensor (CKP) signal from the CKP sensor. It processes the CKP signal into Profile Ignition Pickup (PIP) information and transmits it to the Powertrain Control Module (PCM). The PCM processes the PIP signal along with signals received from the Throttle Position (TP) sensor, Mass Airflow (MAF) sensor, Heated Oxygen Sensor (HO2S), Engine Coolant Temperature (ECT) sensor, Octane Adjust (OCT ADJ), barometric pressure sensor, Vehicle Speed Sensor (VSS), and Brake On-Off (BOO) switch according to a spark advance map programmed into the PCM. The PCM produces a Spark Output (SPOUT) signal which it sends back to the ICM. Using the SPOUT and CKP information, the ICM switches primary current to the ignition coils among the three ignition coils and provides the optimum amount of spark advance and dwell. The ICM module also sends back to the PCM an Ignition Diagnostic Monitor (IDM) signal which the PCM uses to indicate a failure mode and which is also used to provide an RPM signal to the instrument panel tachometer.
Failure Mode Effects Management
During some Electronic Ignition (EI) concerns, the failure mode effects management portion of the ICM will maintain vehicle operation. If the ICM does not receive the SPOUT input, it will automatically default to base timing and turn the ignition coils on and off to provide 10 degrees BTDC spark timing. If the ignition control module does not receive the CKP input, the vehicle will not start or run.
Ignition Diagnostic Monitor
The Ignition Diagnostic Monitor (IDM) is a function of the ICM. The ICM sends information on system failures to the PCM, which stores the information for diagnostic self tests. The IDM signal is also used to drive the vehicle instrument tachometer and/or test tachometer for diagnosis.