Ignition Control Module: Description and Operation

The ignition control unit receives input signals from the altitude sensor, Throttle valve switches, Ignition distributor, Knock sensor, Temperature sensor, and the Injection control unit. Using the information from these sources, the control unit can continually optimize the ignition timing.
The ignition control unit is programmed with two separate ignition timing maps. One is for premium fuel, and the other is for regular fuel. When the engine reaches normal operating temperature, the control unit automatically switches to the premium fuel map which has a more advanced ignition curve.
If ignition knock occurs repeatedly, the control unit will switch to the regular fuel map. The control unit will switch back to the premium fuel map after a certain length of time, or when the engine is restarted.