Testing For Intermittent Problems

Intermittents

Diagnosing intermittents can provide one of the greatest challenges to the technician. When a symptom is determined to be intermittent, careful visual and physical underhood inspection of connectors, wiring harnesses, vacuum lines, components, etc. is required. Look for any vehicle modifications or aftermarket items that may contribute to the symptom.

- Check for any applicable TSBs.

- The Customer Information Worksheet may contain more detailed symptom information.

- Before an in-depth diagnosis begins, start the engine and wiggle wires, tap on components, etc., while listening for an indication of a problem (ex. RPM change, relay clicking).

- The Diagnostic Routines Symptom Flow Charts can help identify an area of concern (refer to "How To Use Diagnostic Routines"). If the Symptom Flow Chart(s) have been performed for the reported symptom(s) and no problem is found, refer to Section 7A for further diagnosis using the EEC-IV Monitor Box/Recorder or Scan Tool. If an EEC-IV Monitor Box or Scan Tool is not available, Section 7A may still be helpful using a breakout box and DVOM.