Intermittent Diagnostic Techniques: Notes

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Intermittent diagnostic techniques help find and isolate the root cause of intermittent concerns associated with the electronic engine control (EEC) system. The information is organized to help find the concern and carry out the repair. The process of finding and isolating an intermittent concern starts with recreating a fault symptom, accumulating PCM data, and comparing that data to typical values, then analyzing the results. Refer to the scan tool manufacturer's instruction manual for the functions described below.

Before proceeding, be sure that:

Customary mechanical system tests and inspections do not reveal a concern. Mechanical component conditions can make a PCM system react abnormally.
Technical Service Bulletins (TSBs) and Online Automotive Service Information System (OASIS) messages, if available, are reviewed.
Quick Test and associated diagnostic subroutines have been completed without finding a concern, and the symptom is still present.