Test Description

The numbers below refer to the step numbers in the diagnostic procedures.

1. 1
   
   The Diagnostic System Check - Engine Controls prompts you to complete some of the basic checks and to store the Freeze Frame/Failure Records data on the scan tool if applicable. This creates an electronic copy of the data captured when the malfunction occurred. The scan tool stores this data on the scan tool for later reference.
2. 2
   
   If a DTC P0201-P0204 is present, the condition causing the misfire is in the fuel injector circuitry. The DTC P0201-P0204 table will diagnose the fuel injectors and circuitry.
3. 3
   
   A visual/physical inspection should include checking for proper electrical connections, pinches in wires, cuts in wires, and clean/tight PCM grounds. Check for air leaks at throttle body mounting and intake manifold sealing surfaces.
4. 4
   
   This step determines if DTC P0301 is the result of a hard malfunction or an intermittent condition.
5. 5
   
   If a spark plug boot is burned, the other plug on that ignition coil may still fire at idle. This step tests the systems ability to produce at least 25,000 volts at the spark plug.
6. 6
   
   If the misfire is not present, you may need to duplicate the conditions in the Freeze Frame data in order to detect a misfire. Depending on the engine load, the conditions may have to be maintained for up to 20 seconds. If the misfire accumulators start to increment, this is an indication that a misfire is present. A history misfire counter will store the number of misfires that have occurred until the DTC is cleared. The current counter must count a total of at least 195 misfires before writing to the history counter.
7. 7
   
   A spark is available at the misfiring cylinder. At this point, the misfire is being caused by one or more of the following conditions: Spark plug, a basic engine problem or leaky fuel injector.
8. 8
   
   A basic engine problem or a fuel injector problem that affects only one cylinder is possible at this point, such as the valve train, the compression, etc.

   If a spark plug is saturated with fuel, or the cylinder is full of fuel, this is a good sign that the fuel injector is stuck open.

9. 9
   
   Check for a fuel injector or engine mechanical problem that may have caused the spark plug to malfunction.
10. 10
    
    No spark on one coil may be caused by an open secondary circuit. Therefore, you will need to check the coils secondary resistance. Resistance readings at greater than 20,000 ohms, but not infinite, will probably not cause a no-start but can cause an engine miss under certain conditions.
11. 11
    
    The test light will blink if the no spark condition is caused by the following items: Ignition coil electrical connections, ignition coil harness, ignition coil, or secondary boot assembly.
12. 13
    
    You can easily check the ignition coil harness by performing the previous step with the ignition coil harness connected to the IC module. Check for a voltage and a ground signal to the ignition coils at the ignition coil electrical connector.
13. 23
    
    Thoroughly check any suspected circuitry for backed out terminals, improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wiring connections, or physical damage to wiring harness
14. 24
    
    Reprogram the replacement PCM and perform the CKP system variation learn procedure. See CKP SYSTEM VARIATION LEARN PROCEDURE  . Refer to latest Techline information for PCM programming.
15. 25
    
    Conditions for setting the DTC P0420 need to be run in order to determine if the catalyst has been damaged from the misfire.