Engine Cranks But Does Not Run

Circuit Description
The Electronic Ignition system uses a waste spark method of spark distribution. The ignition control module (ICM) determines the correct coil sequence based on the CKP sync signal received from the crankshaft position sensor. Two spark plugs connected to the coil fire at the same time. The cylinder on the compression stroke (event cylinder) uses most of the coil's available voltage to fire the spark plug. The cylinder on the exhaust stroke (waste cylinder) uses the remaining coil energy to fire the spark plug.

During crank, the ICM monitors the 18X CKP and CKP sync signals. The ICM uses CKP sync signal to determine the correct cylinder pair to fire first. Only the ICM uses the CKP sync signal. The ICM does not pass the CKP signal to the PCM. While the ICM processes the CKP sync signal, the ICM also monitors the 18X CKP signal. The ICM uses the 18X signal for crankshaft position information and to generate 3X reference pulses. The ICM sends the 18X and 3X reference pulses to the PCM. When the PCM receives these pulses, the PCM energizes all six injectors to allow a priming shot of fuel for the cylinders. After priming the cylinders, the PCM shuts the injectors OFF for the next six, 3X reference pulses. This allows each cylinder a chance to use the fuel from the priming shot. During this waiting period, the PCM receives a camshaft position (CMP) signal pulse. The CMP signal allows the PCM to calculate true sequential fuel injection. If a loss of the CMP signal occur during start-up, the PCM still operates the fuel injectors sequentially. However, fuel injection occurs with a 1 in 6 chance that the injector sequencing is correct.

Diagnostic Aids
An intermittent may be caused by a poor connection, rubbed through wire insulation or a wire broken inside the insulation. Check for the following items:
^ Poor connection or damaged harness. Inspect the PCM harness and connectors for improper mating, broken locks, improperly formed or damaged terminals, poor terminal to wire connection, and damaged harness.
^ Faulty Engine Coolant Temperature Sensor. Using a scan tool, compare Engine Coolant Temperature with Intake Air Temperature on a completely cool engine. Engine Coolant Temperature should be within 10°C of Intake Air Temperature. If not, replace the ECT sensor.

Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table:
5. Determines if the ignition control module (ICM) is receiving the 18X CKP Reference signal. If the 18X CKP signal to the ICM is not present, there will be no RPM, spark, or fuel injector pulses.
6. Ensures that the ICM has the proper voltage supply and ground.
8. Verifies that the ICM is supplying the proper sensor teed voltage.
24. Check for the proper operation of the CKP Sync signal, ICM and related spark system components. Without the CKP Sync signal the ICM is unable to properly sequence the ignition coils.
35. If the 18X and CKP Sync signals to the ICM or the 18X and 3X reference signals to the ICM short together the vehicle will not start and run. However, there will be spark and fuel injector pulses.
46. This vehicle is equipped with a PCM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). When the PCM is being replaced, the new PCM must be programmed.