Introduction

The Electronic Engine Control (EEC-IV) monitor and EEC-IV recorder are useful tools for diagnosing intermittent driveability problems which are not repairable by the normal diagnostic routines. Although this section provides diagnostic procedures and data to be used with the monitor and recorder in a symptom oriented manner, there are several graphs, charts, and tables located under DIAGNOSTIC REFERENCE VALUES and GRAPHS AND CHARTS that are useful without the monitor.
By definition, intermittent is a randomly occurring symptom that sets no hard codes. Often the quick test results in a pass, while the symptom remains. Other results, such as continuous codes, will also be covered in this section.
Before proceding with the procedures in this section, be sure that:
- Customary mechanical system tests and inspections reveal nothing. Remember that a mechanical problem can cause unpredictable results from a good EEC-IV system.
- A quick test and related pinpoint tests have been successfully completed, but the problem still remains.
- A review of the Technical Service Bulletin (TSB) section reveals no applicable article. (If applicable articles are found, perform the actions in the article prior to proceding with tests in this section).
The monitor and recorder function as a window into the EEC-IV system. Through this window the operator is able to view the same sensor values and signals as the Engine Control Assembly (ECA). The ECA uses these values to make decisions which increase performance and decrease emissions. The monitor can display these values during both key ON engine OFF and engine RUNNING conditions. The advantage of the recorder is the ability to take a "snapshot" of selected EEC-IV signals that can be stored and retrieved later.
The diagnostic procedures used in this section is a symptom based approach for isolating the faulty system, circuit, or component. Often a mechanical fault will cause a good EEC-IV system to react abnormally. In such cases, the use of a monitor will enhance the ability to eliminate possible EEC-IV faults and also locate mechanical faults.