Ignition Control

The ignition control (IC) spark timing is the PCM's method of controlling the spark advance and the ignition dwell. The IC spark advance and the ignition dwell are calculated by the PCM using the following inputs:

• Engine speed.
• Crankshaft position (58X reference).
• Engine coolant temperature (ECT) sensor.
• Throttle position (TP) sensor.
• ION sensing module.
• Park/Neutral position (PRNDL input).
• Vehicle speed (vehicle speed sensor).
• PCM and ignition system supply voltage.
• The crankshaft position (CKP) sensor sends the PCM a 58X signal related to the exact position of the crankshaft.

Based on these sensor signals and engine load information, the PCM sends 5 volts to each ignition coil. This module has the function to energize and de-energize the primary ignition coil in response to signals from the PCM. The throttle PCM controls ignition timing and dwell time.