Ignition Control Module
The ignition control module (ICM) assists the powertrain control module (PCM) by operating the ignition coils and injectors 1 and 5. See Fig 1 . The ICM responds to direct commands from the PCM and adjusts ignition timing and coil dwell.
Through the ICM, the PCM adjusts ignition timing based on the following inputs:
- Engine Coolant Temperature
- Engine Speed (Crankshaft Position Sensor)
- Manifold Absolute Pressure
- Throttle Position
The PCM and ICM share many inputs and communicate with each other through the MUX circuit. The ICM receives the vehicle speed sensor input directly, from the sensor and transmits the input to the PCM through a separate circuit.
Additionally, the ICM and PCM both receive the camshaft position sensor and crankshaft position sensor inputs at the same time. While the PCM supplies 8.0 volts to both sensors, it also sends a 8.0 volt signal to the ICM