Defining Intermittent Driveability Symptoms

The EEC-IV monitor and the EEC-IV monitor recorder are useful tools for diagnosing intermittent driveability symptoms or continuous memory Diagnostic Trouble Codes (DTCs) that cannot be resolved through the diagnostics in pinpoint testing. This information contains diagnostic procedures and data using the monitor and recorder in a symptom-oriented or continuous memory DTC manner. If available, the Service Bay Diagnostic System (SBDS) can be used for Intermittent Diagnostics.

Intermittent is a randomly occurring drive symptom for which no hard DTCs (KOEO, KOER) are revealed by quick test. Often the quick test will show "pass DTCs" while the drive symptom still exists.

Before proceeding with diagnosis, be sure that:

- Customary mechanical system tests and inspections reveal nothing. (Remember, mechanical component problems can make a good EEC system react abnormally.)
- Quick test and associated pinpoint diagnosis have been completed, but the symptom or continuous memory DTC is still occurring.
- Review of Technical Service Bulletins (TSBs) for applicable articles.

The monitor and recorder function as a "window" into the EEC system. Through this "window" the user is able to view the sensor values and signals sent to and from the Powertrain Control Module (PCM). The PCM uses these values to make decisions which increase engine performance. The monitor can display these values during both engine OFF (KOEO) and engine running (KOER) conditions. The advantage of the recorder is the ability to take a "snapshot" of selected EEC signals that can be stored and reviewed later.

A basic working knowledge of the EEC system is critical to efficiently troubleshoot the symptom or continuous memory DTC. No diagnostic procedure can account for all the possibilities that may be encountered. This diagnostic procedure only attempts to provide basic steps and methods for isolating possible causes.

The diagnostic procedure used is a symptom or continuous memory DTC based approach to isolating the damaged system, circuit, or sensor. Often a mechanical fault will cause a good EEC system to react abnormally. In those cases, the use of a monitor with this diagnostic procedure will enhance the ability to eliminate possible EEC faults and also locate mechanical faults.