Here is the paragraph about the ICM,
Ignition Control Module (Icm)
The DIS module or ICM, as it's called in later years, monitors the crankshaft sensor signal, then, based on these signals, sends a reference signal to the powertrain control module (PCM) so that correct spark and fuel injector control can be maintained during all driving conditions. During cranking, the module monitors the sync-pulse to begin the ignition firing sequence. Below 400 rpm, the module controls the spark advance by triggering each of the ignition coils at a predetermined interval, based on engine speed only. Above 100 rpm, the PCM controls the electronic spark timing (EST) and compensates for all driving conditions. The module must receive a sync-pulse and then a crank signal, in that order, to enable the engine to start.
The DIS module or Ignition Control Module (ICM) is not repairable. When a module is replaced, the remaining DIS/ICM components must be transferred to the new module.
The IC system is a series of circuits between the ICM and the PCM that are used to send information about the ignition system. This system includes the following circuits:
7X Reference -The CKP sensor generates a signal to the ICM, resulting in a reference pulse which is sent to the PCM. The PCM uses this signal to determine crankshaft position, engine speed and injector pulse width. The engine will not start or run if this circuit is open or grounded.
Reference low-This wire is grounded through the module and insures that the ground circuit has no voltage drop between the ICM and the PCM which may affect engine performance.
Ignition control 1 & 2 -The PCM sends the Ignition Control (IC) pulses to the ICM on these circuits. These signals are similar to the 7X reference pulse except that the PCM uses sensor inputs to determine the pulse timing to control spark advance. When the PCM receives the 7X signal, it will determine which pair of cylinders will be fired. (1-4 or 2-3). It will tell the ICM which cylinder pair will be fired.