Intermittent Diagnostic Techniques: Notes

Intermittent diagnostic techniques help find and isolate the root cause of intermittent faults associated with the Electronic Engine Control System. The information is organized to help find the fault and perform the repair. The process of finding and isolating an intermittent 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 users manual for functions described below.

Before proceeding, be sure that:

• Customary mechanical system tests and inspections do not reveal a concern. (Remember, mechanical component conditions can make a PCM system react abnormally.)
• Technical Service Bulletins (TSBs), if available, are reviewed.
• Quick Test and associated Diagnostic Subroutines have been completed without finding a fault, and the symptom is still present.