Electronic Ignition System

The Electronic Ignition (EI) system consists of coil packs, EI modules, Crankshaft Position (CKP) sensor (2 used), Camshaft Position (CMP) sensor, wiring harness and the Ignition Control (IC) portion of the Powertrain Control Module (PCM). Input from the CKP sensor and EI modules is used by the PCM to control ignition timing and triggering of fuel injectors.

• Crankshaft Position Sensor (7X/24X Signal)
  
  Engine is equipped with 2 Crankshaft Position (CKP) sensors. See Figure . The CKP sensor "B" is a variable reluctance sensor. The magnetic field of the sensor is altered by a crankshaft mounted reluctor wheel that has seven machined slots, 6 of which are equally spaced 60 degrees apart. The seventh slot is spaced 10 degrees after one of the 60 degree slots. This sensor provides the ICM with 7X signals or 7 pulses for each revolution of the crankshaft. The pulse from the 10 degree slot is known as the sync pulse. Both of the sensor circuits are connected to the ICM. A signal converter within the ICM produces digital 3X output pulse to the PCM, the 3X reference is known as the low resolution engine speed signal. The CKP sensor "A" contains a hall-effect switch. A hall-effect switch is a solid state switching device that produces a digital ON/OFF pulse when a rotating element passes between the sensor tip and a magnet. This rotating element is called an interrupter ring or blade. In this case the interrupter ring has 24 evenly spaced blades and windows and is part of the crankshaft damper assembly. This sensor provides PCM with 24X signals or 24 identical pulses per crankshaft revolution. The 24X signal is used for enhanced smoothness and idle stability at a lower calibrated RPM. The PCM supplies the sensor with a 12-volt reference, low reference, and signal circuits.
• Ignition Control Module & Ignition Coils
  
  There are 3 dual tower ignition coils are mounted to the Ignition Control Module (ICM) and are serviced individually. See Figure . The ICM performs the following functions:
  • ICM receives and processes the signals from the CKP sensor "B".
  • ICM determines the correct direction of the crankshaft rotation, and cuts spark and fuel delivery to prevent damage from backfiring if reverse rotation is detected.
  • ICM determines the correct coil triggering sequence, based on the 7X CKP signal. This coil sequencing occurs at start-up, and is remembered by the ICM. After engine is running, ICM will continue to trigger the coils in the correct sequence.
  • ICM produces and inputs 3X reference signals to PCM. The ICM contains the coil driver circuits that command the coils to operate.