Circuits Affecting Ignition Control

To properly control ignition timing, the PCM relies on the following information:
^ Engine load (manifold pressure or vacuum)
^ Atmospheric (barometric) pressure
^ Engine temperature
^ Intake air temperature
^ Crankshaft position
^ Engine speed (RPM)

The Ignition Control (IC) system consists of the following components:
^ Ignition coil/modules
^ 24X crankshaft position sensor
^ Powertrain Control Module (PCM)
^ All connecting wires

The Ignition Control utilizes the following to control spark timing functions:
^ 24X signal - The 24X crankshaft position sensor sends a signal to the PCM. The PCM uses this signal to determine crankshaft position. The PCM also utilizes this signal to trigger the fuel injectors.
^ Ignition Control (IC) circuits - The PCM uses these circuits to trigger the ignition coil/modules. The PCM uses the crankshaft reference signal to calculate the amount of spark advance needed.